Prp24: Difference between revisions

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U6 is considered to be one of the most catalytically important snRNAs in the spliceosome, as it interacts directly with the 5' splice site through base pairing <ref name="Fortner">PMID:8299941</ref>. It is thought to undergoe three conformational changes throughout the entire process of splicing and splicesome assembly; it exists as one conformation as free U6 snRNP, another conformation as part of the U4/U6 di-snRNP and a third conformation associated with U2 and the pre-mRNA <ref name="Jandrositz">PMID:7882985</ref>. In addition to Prp24, U6 is associated with seven other proteins, Lsm 2-8, which form a ring around the 3' portion of the U6 snRNA <ref name="Karaduman2008">PMID:18971323</ref>.

The U4 snRNA is though to be non-catalytic because it leaves the spliceosome before the transesterification reactions occur <ref name="Staley"/>. Its function is instead thought to be aiding U6 in maintaining a conformation that will enable it to interact with U2 and the 5' splice site. The U4 snRNP contains the U4 snRNA, a ring complex of the Sm proteins B-G, and the proteins Prp3, Prp4, and Snu13 <ref name="Brow review"/>.

The U4 snRNA is though to be non-catalytic because it leaves the spliceosome before the transesterification reactions occur <ref name="Staley"/>. Its function is instead thought to be aiding U6 in maintaining a conformation that will enable it to interact with U2 and the 5' splice site <ref name="Madhani">PMID:2149118</ref>. The U4 snRNP contains the U4 snRNA, a ring complex of the Sm proteins B-G, and the proteins Prp3, Prp4, and Snu13 <ref name="Brow review"/>.

The annealing of the U4 and U6 snRNAs to form the U4/U6 di-snRNP complex, which contains the additional proteins Prp6 and Prp31, is an essential process in the formation of the spliceosome <ref name="Brow review"/>. It enables interaction with the U5 snRNP to form the U4/U6.U5 complex which serves to deliver the U5 and U6 snRNPs to the appropriate sites in the pre-spliceosome complex to form a catalytically active spliceosome upon departure of U1 and U4 <ref name="Brow review"/>.

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===Additional Interactions===

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 (reference Vaidya et al. 1996). However, further investigation failed to produce evidence of an interaction between the two proteins, but the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome (reference Vaidya and Vijayraghavan 1998). It has also been suggested that Prp24 may serve in the destabilization of the U4/U6 complex to allow base pairing of U5 or in destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP, but again, there have been no studies showing support for these roles of the protein.

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 (reference Vaidya et al. 1996). However, further investigation failed to produce evidence of an interaction between the two proteins, but the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome (reference Vaidya and Vijayraghavan 1998). It has also been suggested that Prp24 may serve in the destabilization of the U4/U6 complex to allow base pairing of U5 (reference) or in destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP, but again, there have been no studies showing support for these roles of the protein (Vidaver et al. 1999).

== References ==

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@@ Line 16: / Line 16: @@
 U6 is considered to be one of the most catalytically important snRNAs in the spliceosome, as it interacts directly with the 5' splice site through base pairing <ref name="Fortner">PMID:8299941</ref>.  It is thought to undergoe three conformational changes throughout the entire process of splicing and splicesome assembly; it exists as one conformation as free U6 snRNP, another conformation as part of the U4/U6 di-snRNP and a third conformation associated with U2 and the pre-mRNA <ref name="Jandrositz">PMID:7882985</ref>.  In addition to Prp24, U6 is associated with seven other proteins, Lsm 2-8, which form a ring around the 3' portion of the U6 snRNA <ref name="Karaduman2008">PMID:18971323</ref>.
-The U4 snRNA is though to be non-catalytic because it leaves the spliceosome before the transesterification reactions occur <ref name="Staley"/>.  Its function is instead thought to be aiding U6 in maintaining a conformation that will enable it to interact with U2 and the 5' splice site.  The U4 snRNP contains the U4 snRNA, a ring complex of the Sm proteins B-G, and the proteins Prp3, Prp4, and Snu13 <ref name="Brow review"/>.
+The U4 snRNA is though to be non-catalytic because it leaves the spliceosome before the transesterification reactions occur <ref name="Staley"/>.  Its function is instead thought to be aiding U6 in maintaining a conformation that will enable it to interact with U2 and the 5' splice site <ref name="Madhani">PMID:2149118</ref>.  The U4 snRNP contains the U4 snRNA, a ring complex of the Sm proteins B-G, and the proteins Prp3, Prp4, and Snu13 <ref name="Brow review"/>.
 The annealing of the U4 and U6 snRNAs to form the U4/U6 di-snRNP complex, which contains the additional proteins Prp6 and Prp31, is an essential process in the formation of the spliceosome <ref name="Brow review"/>.  It enables interaction with the U5 snRNP to form the U4/U6.U5 complex which serves to deliver the U5 and U6 snRNPs to the appropriate sites in the pre-spliceosome complex to form a catalytically active spliceosome upon departure of U1 and U4 <ref name="Brow review"/>.
@@ Line 68: / Line 68: @@
 ===Additional Interactions===
-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 (reference Vaidya et al. 1996).  However, further investigation failed to produce evidence of an interaction between the two proteins, but the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome (reference Vaidya and Vijayraghavan 1998).  It has also been suggested that Prp24 may serve in the destabilization of the U4/U6 complex to allow base pairing of U5 or in destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP, but again, there have been no studies showing support for these roles of the protein.
+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 (reference Vaidya et al. 1996).  However, further investigation failed to produce evidence of an interaction between the two proteins, but the authors maintained that a transient interaction between Prp24 and Prp21 may exist in an intermediate form of the assembling spliceosome (reference Vaidya and Vijayraghavan 1998).  It has also been suggested that Prp24 may serve in the destabilization of the U4/U6 complex to allow base pairing of U5 (reference) or in destabilization of U6 from U2 upon completion of splicing to release free U6 snRNP, but again, there have been no studies showing support for these roles of the protein (Vidaver et al. 1999).
 == References ==
 <references/>