2fmx: Difference between revisions

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[[Image:2fmx.jpg|left|200px]]<br /><applet load="2fmx" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:2fmx.jpg|left|200px]]<br /><applet load="2fmx" size="350" color="white" frame="true" align="right" spinBox="true"

caption="2fmx, resolution 1.82Å" />

'''An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg(2+)'''<br />

==Overview==

Mg2+ is essential for guanosine triphosphatase activity and plays key, roles in guanine nucleotide binding and preserving the structural, integrity of GTP-binding proteins. To understand the structural basis for, Mg2+ function during the GDP/GTP exchange process, we determined the, crystal structure of Delta9-Sar1-GDP at low Mg2+ concentration at 1.8A., Two Sar1-GDP molecules in the crystal form a dimer with Mg2+ presenting, only in molecule B but not in molecule A. The absence of Mg2+ induces, significant conformational changes in the switch I region in molecule A, that shows similarities with those of Ha-Ras bound to Sos. The current, structure reveals an important regulatory role for Mg2+. We suggest that, guanine nucleotide exchange factor may utilize this feature to generate an, open conformation for GDP/GTP exchange. Furthermore, we propose a, mechanism for COPII assembly and disassembly in which dimerization of Sar1, plays an important role.

Mg2+ is essential for guanosine triphosphatase activity and plays key roles in guanine nucleotide binding and preserving the structural integrity of GTP-binding proteins. To understand the structural basis for Mg2+ function during the GDP/GTP exchange process, we determined the crystal structure of Delta9-Sar1-GDP at low Mg2+ concentration at 1.8A. Two Sar1-GDP molecules in the crystal form a dimer with Mg2+ presenting only in molecule B but not in molecule A. The absence of Mg2+ induces significant conformational changes in the switch I region in molecule A that shows similarities with those of Ha-Ras bound to Sos. The current structure reveals an important regulatory role for Mg2+. We suggest that guanine nucleotide exchange factor may utilize this feature to generate an open conformation for GDP/GTP exchange. Furthermore, we propose a mechanism for COPII assembly and disassembly in which dimerization of Sar1 plays an important role.

==About this Structure==

2FMX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cricetulus_griseus Cricetulus griseus] with SO4, MG and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=2FMX OCA].

2FMX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cricetulus_griseus Cricetulus griseus] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=GDP:'>GDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2FMX OCA].

==Reference==

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[[Category: sar1]]

''Page seeded by [http://~~ispc~~.weizmann.ac.il/oca OCA ] on ~~Wed Nov~~ 21 10:38:~~21 2007~~''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:23:03 2008''

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@@ Line 1: / Line 1: @@
-[[Image:2fmx.jpg|left|200px]]<br /><applet load="2fmx" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:2fmx.jpg|left|200px]]<br /><applet load="2fmx" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="2fmx, resolution 1.82&Aring;" />
 '''An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg(2+)'''<br />
 ==Overview==
-Mg2+ is essential for guanosine triphosphatase activity and plays key, roles in guanine nucleotide binding and preserving the structural, integrity of GTP-binding proteins. To understand the structural basis for, Mg2+ function during the GDP/GTP exchange process, we determined the, crystal structure of Delta9-Sar1-GDP at low Mg2+ concentration at 1.8A., Two Sar1-GDP molecules in the crystal form a dimer with Mg2+ presenting, only in molecule B but not in molecule A. The absence of Mg2+ induces, significant conformational changes in the switch I region in molecule A, that shows similarities with those of Ha-Ras bound to Sos. The current, structure reveals an important regulatory role for Mg2+. We suggest that, guanine nucleotide exchange factor may utilize this feature to generate an, open conformation for GDP/GTP exchange. Furthermore, we propose a, mechanism for COPII assembly and disassembly in which dimerization of Sar1, plays an important role.
+Mg2+ is essential for guanosine triphosphatase activity and plays key roles in guanine nucleotide binding and preserving the structural integrity of GTP-binding proteins. To understand the structural basis for Mg2+ function during the GDP/GTP exchange process, we determined the crystal structure of Delta9-Sar1-GDP at low Mg2+ concentration at 1.8A. Two Sar1-GDP molecules in the crystal form a dimer with Mg2+ presenting only in molecule B but not in molecule A. The absence of Mg2+ induces significant conformational changes in the switch I region in molecule A that shows similarities with those of Ha-Ras bound to Sos. The current structure reveals an important regulatory role for Mg2+. We suggest that guanine nucleotide exchange factor may utilize this feature to generate an open conformation for GDP/GTP exchange. Furthermore, we propose a mechanism for COPII assembly and disassembly in which dimerization of Sar1 plays an important role.
 ==About this Structure==
-FMX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cricetulus_griseus Cricetulus griseus] with SO4, MG and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2FMX OCA].
+FMX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cricetulus_griseus Cricetulus griseus] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=GDP:'>GDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2FMX OCA].
 ==Reference==
@@ Line 26: / Line 26: @@
 [[Category: sar1]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 10:38:21 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:23:03 2008''