Prp24: Difference between revisions

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<StructureSection load='2ghp' size='450' side='right' scene='Sandbox_Reserved_340/2ghp/1' caption='Yeast N-terminal 3 RNA binding domains of splicing factor Prp24 (PDB code [[2ghp]]).'>
{{Template:Sandbox_Reserved_BCMB307}}
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{{STRUCTURE_2ghp|  PDB=2ghp  |  SCENE=Sandbox_Reserved_340/2ghp/1  }}
'''Prp24''' ('''Pr'''e-mRNA splicing '''P'''rotein '''24''') is a [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae ''Saccharomyces cerevisiae''] yeast protein that functions in the formation of base pair interactions between the [http://en.wikipedia.org/wiki/U6_spliceosomal_RNA U6] and [http://en.wikipedia.org/wiki/U4_spliceosomal_RNA U4] [http://en.wikipedia.org/wiki/SnRNP snRNPs (small nuclear ribonucleoproteins)] to form the U4/U6 di-snRNP during the assembly of the [http://en.wikipedia.org/wiki/Spliceosome spliceosome]  <ref name="Bae">PMID:17320109</ref>.  This protein contains four RNA recognition motifs (RRMs) that function in the binding of Prp24 to U6 snRNA <ref name="Bae"/>.  These RRM domains are conserved in structure and sequence in proteins orthologous to Prp24 in ''Homo sapiens'' and ''Schizosaccharomyces pombe'', as well as in other proteins containing RRMs <ref name="Rader">PMID:12458792</ref>.
'''Prp24''' ('''Pr'''e-mRNA splicing '''P'''rotein '''24''') is a [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae ''Saccharomyces cerevisiae''] yeast protein that functions in the formation of base pair interactions between the [http://en.wikipedia.org/wiki/U6_spliceosomal_RNA U6] and [http://en.wikipedia.org/wiki/U4_spliceosomal_RNA U4] [http://en.wikipedia.org/wiki/SnRNP snRNPs (small nuclear ribonucleoproteins)] to form the U4/U6 di-snRNP during the assembly of the [http://en.wikipedia.org/wiki/Spliceosome spliceosome]  <ref name="Bae">PMID:17320109</ref>.  This protein contains four RNA recognition motifs (RRMs) that function in the binding of Prp24 to U6 snRNA <ref name="Bae"/>.  These RRM domains are conserved in structure and sequence in proteins orthologous to Prp24 in ''Homo sapiens'' and ''Schizosaccharomyces pombe'', as well as in other proteins containing RRMs <ref name="Rader">PMID:12458792</ref>.


== Introduction ==
== Introduction ==
[[Image:Spliceosome.jpg |frame|left| Figure 1.  Assembly and disassembly of the spliceosome in ''Saccharomyces cerevisiae'' (after Staley and Guthrie 1998 <ref name="Staley"/>)]]
[[Image:Spliceosome.jpg |frame|left| Figure 1.  Assembly and disassembly of the spliceosome in ''Saccharomyces cerevisiae'' (after Staley and Guthrie 1998 <ref name="Staley"/>)]]
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[[Image:Transester.jpg |frame|left| Figure 2.  The transesterificiation reactions of pre-mRNA splicing (after Brow 2002<ref name="Brow review"/>) ]]
[[Image:Transester.jpg |frame|left| Figure 2.  The transesterificiation reactions of pre-mRNA splicing (after Brow 2002<ref name="Brow review"/>) ]]
{{Clear}}
=== Pre-mRNA Splicing ===
=== Pre-mRNA Splicing ===


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== Structure ==
== Structure ==


<Structure load='2ghp' size='300' frame='true' align='right' caption='' scene='Sandbox_Reserved_340/2ghp/3'/>


The key structural elements of Prp24 are the conserved RNA recognition motifs (RRMs).  These motifs are found in many proteins with RNA binding properties and contain conserved RNP elements that are recognizable by their primary sequence <ref name="Shannon"/>.  For several years, Prp24 was thought to contain three RRMs, termed RRM 1, RRM 2, and RRM 3 <ref name="Shannon"/>.  However, analysis of homologs of Prp24 from several different species allowed the identification of a fourth RRM in Prp24 of ''S. cerevisiae'', albeit one that was much less highly conserved and not easily recognizable by its RNP-consensus domain <ref name="Rader"/>.
The key structural elements of Prp24 are the conserved RNA recognition motifs (RRMs).  These motifs are found in many proteins with RNA binding properties and contain conserved RNP elements that are recognizable by their primary sequence <ref name="Shannon"/>.  For several years, Prp24 was thought to contain three RRMs, termed RRM 1, RRM 2, and RRM 3 <ref name="Shannon"/>.  However, analysis of homologs of Prp24 from several different species allowed the identification of a fourth RRM in Prp24 of ''S. cerevisiae'', albeit one that was much less highly conserved and not easily recognizable by its RNP-consensus domain <ref name="Rader"/>.
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Prp24 co-immunoprecipitates with free U6 and U4/U6 di-snRNP, indicating that it is closely associated with these particles <ref name="Shannon"/><ref name="Ghetti">PMID:7585243</ref>.  Initial investigation of the structure showed that Prp24 very likely binds directly to the 40-43 nucleotides of U6 based on chemical modification of naked U6 snRNA compared to free U6 snRNP<ref name="Jandrositz"/>.  Further investigation suggested that Prp24 binds within the 30-56 nucleotide region of free U6, as well as to stem II of U4/U6 in the 39-56 and 67-70 nucleotide regions of U6 <ref name="Ghetti"/>.   
Prp24 co-immunoprecipitates with free U6 and U4/U6 di-snRNP, indicating that it is closely associated with these particles <ref name="Shannon"/><ref name="Ghetti">PMID:7585243</ref>.  Initial investigation of the structure showed that Prp24 very likely binds directly to the 40-43 nucleotides of U6 based on chemical modification of naked U6 snRNA compared to free U6 snRNP<ref name="Jandrositz"/>.  Further investigation suggested that Prp24 binds within the 30-56 nucleotide region of free U6, as well as to stem II of U4/U6 in the 39-56 and 67-70 nucleotide regions of U6 <ref name="Ghetti"/>.   
<Structure load='2ghp' size='300' frame='true' align='right' caption='' scene='Sandbox_Reserved_340/2ghp/3'/>
 
The main function of Prp24 seems to be directly related to formation of the U4/U6 complex, particularly based on the evidence that Prp24 is present in U6 and U4/U6, but not U4/U6.U5 <ref name="Shannon"/><ref name="Ghetti"/><ref name="Jandrositz"/>.  Prp24 greatly increases the rate and efficiency of U4/U6 annealing <ref name="Raghunathan">PMID:9452384</ref> and mutations in Prp24 have been shown to prevent the formation of the U4/U6 di-snRNP <ref name="Lygerou">PMID:10022888</ref>.  Although the exact mechanism by which Prp24 promotes annealing of U4 and U6 is not known, it has been suggested that Prp24 may stabilize the secondary structure of U6 to allow it to interact with U4 in order to allow formation of U4/U6 <ref name="Vidaver"/>.
The main function of Prp24 seems to be directly related to formation of the U4/U6 complex, particularly based on the evidence that Prp24 is present in U6 and U4/U6, but not U4/U6.U5 <ref name="Shannon"/><ref name="Ghetti"/><ref name="Jandrositz"/>.  Prp24 greatly increases the rate and efficiency of U4/U6 annealing <ref name="Raghunathan">PMID:9452384</ref> and mutations in Prp24 have been shown to prevent the formation of the U4/U6 di-snRNP <ref name="Lygerou">PMID:10022888</ref>.  Although the exact mechanism by which Prp24 promotes annealing of U4 and U6 is not known, it has been suggested that Prp24 may stabilize the secondary structure of U6 to allow it to interact with U4 in order to allow formation of U4/U6 <ref name="Vidaver"/>.


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Several additional roles for Prp24 have been suggested in spliceosome assembly/disassembly, although nothing has been sufficiently supported.  A genetic interaction in which Prp24 mutation suppressed a Prp21 (a component of the U2 snRNP) mutation suggested that the two proteins may interact during the base pairing of U2 and U6 at the 5' splice site; however, further investigation failed to produce evidence of a definite interaction between the two proteins, although the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome <ref name="Vaidya"/>.  It has also been suggested that Prp24 may also assist in the formation of U4/U5.U6 <ref name="Ryan">PMID:12212846</ref> or in the destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP,<ref name="Vidaver"/>, but there is insufficient evidence to conclusively support these functions of Prp24.
Several additional roles for Prp24 have been suggested in spliceosome assembly/disassembly, although nothing has been sufficiently supported.  A genetic interaction in which Prp24 mutation suppressed a Prp21 (a component of the U2 snRNP) mutation suggested that the two proteins may interact during the base pairing of U2 and U6 at the 5' splice site; however, further investigation failed to produce evidence of a definite interaction between the two proteins, although the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome <ref name="Vaidya"/>.  It has also been suggested that Prp24 may also assist in the formation of U4/U5.U6 <ref name="Ryan">PMID:12212846</ref> or in the destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP,<ref name="Vidaver"/>, but there is insufficient evidence to conclusively support these functions of Prp24.
</StructureSection>
__NOTOC__
==3D structures of pre-mRNA-splicing factors==
[[pre-mRNA-splicing factor]]


== References ==
== References ==
<references/>
<references/>

Latest revision as of 07:43, 1 January 2015

Yeast N-terminal 3 RNA binding domains of splicing factor Prp24 (PDB code 2ghp).

Drag the structure with the mouse to rotate


3D structures of pre-mRNA-splicing factors

pre-mRNA-splicing factor

References

Proteopedia Page Contributors and Editors (what is this?)

Kara Perdue, Michal Harel, OCA, Alexander Berchansky