Single stranded binding protein - Revision history

Michal Harel at 11:01, 6 February 2019

2019-02-06T11:01:18Z

← Older revision		Revision as of 11:01, 6 February 2019
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	<StructureSection load='1eyg' size='400' side='right' frame='true' caption='' scene=''>		<StructureSection load='1eyg' size='400' side='right' frame='true' caption='E. coli single-stranded DNA-binding protein chymotryptic fragment complex with DNA (PDB code [[1eyg]])' scene=''>
	Single Stranded DNA-Binding Protein (SSB)		Single Stranded DNA-Binding Protein (SSB)
	==Overview==		==Overview==

Alexander Berchansky at 11:56, 11 December 2014

2014-12-11T11:56:00Z

← Older revision		Revision as of 11:56, 11 December 2014
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			<StructureSection load='1eyg' size='400' side='right' frame='true' caption='' scene=''>
	Single Stranded DNA-Binding Protein (SSB)		Single Stranded DNA-Binding Protein (SSB)
	==Overview==		==Overview==
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	==Structure of ''E. coli'' SSB==		==Structure of ''E. coli'' SSB==

	~~<StructureSection load='1eyg' size='400' side='right' frame='true' caption='Structure of Single Stranded DNA-Binding Protein bound to ssDNA (PDB entry [[1eyg]])' scene=''>~~
	SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. This is a common theme among DNA binding proteins. The cause is presumed to be that the protein has less ion decoration at lower salt levels. And it could be that the subunits interact with each other through salt bridges to remain close to each other and the DNA. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.		SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. This is a common theme among DNA binding proteins. The cause is presumed to be that the protein has less ion decoration at lower salt levels. And it could be that the subunits interact with each other through salt bridges to remain close to each other and the DNA. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.

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	<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.		<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.

	~~</StructureSection>~~

	==Other SSB Structures==		==Other SSB Structures==
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	As single-stranded DNA binding proteins are utilized in some of the most important aspects of DNA metabolism, they are used extensively in DNA replication, repair and recombination<ref>PMID: 2087220</ref>. Most SSBs use one or more subunits with an OB-fold motif to bind securely and preferentially to ssDNA. A few specific SSBs (such as RecA and adenovirus DBP) do not use the OB-fold, instead relying on electrostatic and stacking interactions as well as hydrogen bonding<ref>Shamoo, Yousif. “Single Stranded DNA binding proteins.” ‘’Encyclopedia of Life Sciences.’’ MacMillan Publishers Ltd, Nature Publishing Group; 2002</ref>.		As single-stranded DNA binding proteins are utilized in some of the most important aspects of DNA metabolism, they are used extensively in DNA replication, repair and recombination<ref>PMID: 2087220</ref>. Most SSBs use one or more subunits with an OB-fold motif to bind securely and preferentially to ssDNA. A few specific SSBs (such as RecA and adenovirus DBP) do not use the OB-fold, instead relying on electrostatic and stacking interactions as well as hydrogen bonding<ref>Shamoo, Yousif. “Single Stranded DNA binding proteins.” ‘’Encyclopedia of Life Sciences.’’ MacMillan Publishers Ltd, Nature Publishing Group; 2002</ref>.
	~~</StructureSection>~~

	==See Also==		==See Also==

Refayat Ahsen at 08:47, 21 November 2013

2013-11-21T08:47:29Z

← Older revision		Revision as of 08:47, 21 November 2013
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	~~Sandbox~~ Single Stranded DNA-Binding Protein (SSB)		Single Stranded DNA-Binding Protein (SSB)
	==Overview==		==Overview==
	'''Single-stranded DNA-binding protein''' '''(SSB)''' binds to single-stranded regions of DNA. This binding serves a variety of functions - it prevents the strands from hardening too early during replication, it protects the single-stranded DNA from being broken down by nucleases during repair, and it removes the secondary structure of the strands so that other enzymes are able to access them and act effectively upon the strands<ref>PMID:2087220</ref>.		'''Single-stranded DNA-binding protein''' '''(SSB)''' binds to single-stranded regions of DNA. This binding serves a variety of functions - it prevents the strands from hardening too early during replication, it protects the single-stranded DNA from being broken down by nucleases during repair, and it removes the secondary structure of the strands so that other enzymes are able to access them and act effectively upon the strands<ref>PMID:2087220</ref>.

Rachel Craig at 13:10, 20 November 2013

2013-11-20T13:10:29Z

← Older revision		Revision as of 13:10, 20 November 2013
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	<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.		<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.

			</StructureSection>

	==Other SSB Structures==		==Other SSB Structures==

Rachel Craig: /* Structure of ''E. coli'' SSB */

2013-11-20T13:09:50Z

Structure of ''E. coli'' SSB

← Older revision		Revision as of 13:09, 20 November 2013
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	Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple basic residues, or <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many negatively charged, or <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.		Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple basic residues, or <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many negatively charged, or <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.
	~~</StructureSection>~~

	==Binding Interactions in the Active Site==		==Binding Interactions in the Active Site==

Rachel Craig at 13:06, 20 November 2013

2013-11-20T13:06:01Z

← Older revision		Revision as of 13:06, 20 November 2013
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	<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.		<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.

	~~</StructureSection>~~

Rachel Craig at 13:05, 20 November 2013

2013-11-20T13:05:26Z

← Older revision		Revision as of 13:05, 20 November 2013
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	<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.		<scene name='56/566528/Gly_15/2'>Gly15</scene> is believed to play an important role in binding the RecA protein. SSB will interact with the protein RecA to enable recombination, because RecA will recognize SSB and replace it on the strand. In DNA repair, SSB will bind to the damaged strand to protect it. And eventually it will attract repair enzymes which will replace SSB and begin repair mechanisms. Mutations in <scene name='56/566528/Gly_15/2'>Gly15</scene> have been shown to have extreme effects on recombinational repair. SSB is also thought to bind with exonuclease I, DNA polymerase II, and a protein n, which is a part of the primosome complex and used to help synthesize RNA primers for the lagging strand <ref>PMID: 2087220</ref>.

			</StructureSection>

Rachel Craig at 12:30, 20 November 2013

2013-11-20T12:30:18Z

← Older revision		Revision as of 12:30, 20 November 2013
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	SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. This is a common theme among DNA binding proteins. The cause is presumed to be that the protein has less ion decoration at lower salt levels. And it could be that the subunits interact with each other through salt bridges to remain close to each other and the DNA. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.		SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. This is a common theme among DNA binding proteins. The cause is presumed to be that the protein has less ion decoration at lower salt levels. And it could be that the subunits interact with each other through salt bridges to remain close to each other and the DNA. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.

	Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.		Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple basic residues, or <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many negatively charged, or <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.
	</StructureSection>		</StructureSection>

Rachel Craig at 12:26, 20 November 2013

2013-11-20T12:26:42Z

← Older revision		Revision as of 12:26, 20 November 2013
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	<StructureSection load='1eyg' size='400' side='right' frame='true' caption='Structure of Single Stranded DNA-Binding Protein bound to ssDNA (PDB entry [[1eyg]])' scene=''>		<StructureSection load='1eyg' size='400' side='right' frame='true' caption='Structure of Single Stranded DNA-Binding Protein bound to ssDNA (PDB entry [[1eyg]])' scene=''>
	SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.		SSB proteins have been identified in many different organisms, but the most well understood SSB remains the SSB of ''E. coli''. ''E. coli'' SSB is a homotetramer consisting of <scene name='56/566528/Homotetramer/1'>four identical subunits</scene> which are each about 19 kDa in size <ref>PMID:2087220</ref>. There are two different binding modes of the ''E. coli'' SSB when it complexes with ssDNA<ref>PMID:11993998</ref>. Regulation of these modes has been found to be dependent on salt concentration, in addition to other unknown factors. Under low salt conditions, the protein is less efficient as only two of the four identical subunits of ''E. coli'' SSB were found to bind to the ssDNA <ref>PMID:11993998</ref>. This is a common theme among DNA binding proteins. The cause is presumed to be that the protein has less ion decoration at lower salt levels. And it could be that the subunits interact with each other through salt bridges to remain close to each other and the DNA. Under high salt concentrations, however, all four subunits of the homotetramer bind to the ssDNA, increasing the number of nucleotides in contact with the SSB and thus favoring SSB-ssDNA interactions. Depending on the salt concentration and other factors, estimates of the size of the site of interaction between SSB and ssDNA range anywhere from 30 to 73 nucleotides for each tetramer <ref>PMID:11993998</ref>.

	Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.		Active ''E. coli'' SSB is made of a homotetramer with extensive DNA binding domains that bind to <scene name='56/566528/Dna/1'>a single strand of DNA</scene><ref>PMID:2087220</ref>. The tetramers consist of <scene name='56/566528/E_coli_ssb_alpha_helices/1'>α-helices</scene>, <scene name='56/566528/Beta_sheets/2'>β-sheets</scene>, and random coils. Each subunit contains an α-helix and several β-sheets. The secondary structure also includes a NH2 terminus, which consists of multiple <scene name='56/566528/Basic_residues/2'>positively charged amino acids</scene>. The DNA-binding domain lies within 115 amino acid residues from this terminus. The COOH terminus includes many <scene name='56/566528/Acidic_residues/5'>acidic amino acids</scene> <ref>PMID:2087220</ref>.

Rachel Craig at 01:54, 20 November 2013

2013-11-20T01:54:52Z

← Older revision		Revision as of 01:54, 20 November 2013
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	==Binding Interactions in the Active Site==		==Binding Interactions in the Active Site==

	<scene name='56/566528/Ssdna/1'>Single-stranded DNA</scene> can interact with SSB through hydrogen bonds, stacking, or electrostatic interactions. Though SSB proteins are found in a variety of different organisms, most interactions between SSB and ssDNA happen through the common structural motif of an oligosaccharide/oligonucleotide binding site, referred to as the <scene name='56/566528/Ob_fold/4'>OB fold</scene> <ref>Shamoo, Yousif. “Single Stranded DNA binding proteins.” ‘’Encyclopedia of Life Sciences.’’ MacMillan Publishers Ltd, Nature Publishing Group; 2002</ref>. The OB fold allows SSB to bind preferentially to ssDNA. Each subunit of a SSB has an <scene name='56/566528/Ob_fold/1'>OB fold</scene> (the SSB of E. coli thus has <scene name='56/566528/Ob_fold/2'>four OB folds</scene>, one per each of its <scene name='56/566528/Homotetramer/1'>four identical subunits</scene>). This fold consists of a <scene name='56/566528/Beta_barrel/1'>5 stranded β barrel</scene> that ends in an <scene name='56/566528/Beta_barrel/2'>α-helix</scene>.		<scene name='56/566528/Ssdna/1'>Single-stranded DNA</scene> can interact with SSB through hydrogen bonds, stacking, or electrostatic interactions. Though SSB proteins are found in a variety of different organisms, most interactions between SSB and ssDNA happen through the common structural motif of an oligosaccharide/oligonucleotide binding site, referred to as the <scene name='56/566528/Ob_fold/4'>OB fold</scene> <ref>Shamoo, Yousif. “Single Stranded DNA binding proteins.” ‘’Encyclopedia of Life Sciences.’’ MacMillan Publishers Ltd, Nature Publishing Group; 2002</ref>. The OB fold allows SSB to bind preferentially to ssDNA. Each subunit of a SSB has an <scene name='56/566528/Ob_fold/1'>OB fold</scene> (the SSB of E. coli thus has <scene name='56/566528/Ob_fold/2'>four OB folds</scene>, one per each of its <scene name='56/566528/Homotetramer/1'>four identical subunits</scene>). This fold consists of a <scene name='56/566528/Beta_barrel/1'>5 stranded β barrel</scene> that ends in an <scene name='56/566528/Beta_barrel/2'>α-helix</scene>.