9j8p

Structural highlights

Function

STPAP_HUMAN Poly(A) polymerase that creates the 3'-poly(A) tail of specific pre-mRNAs. Localizes to nuclear speckles together with PIP5K1A and mediates polyadenylation of a select set of mRNAs, such as HMOX1. In addition to polyadenylation, it is also required for the 3'-end cleavage of pre-mRNAs: binds to the 3'UTR of targeted pre-mRNAs and promotes the recruitment and assembly of the CPSF complex on the 3'UTR of pre-mRNAs. In addition to adenylyltransferase activity, also has uridylyltransferase activity. However, the ATP ratio is higher than UTP in cells, suggesting that it functions primarily as a poly(A) polymerase. Acts as a specific terminal uridylyltransferase for U6 snRNA in vitro: responsible for a controlled elongation reaction that results in the restoration of the four 3'-terminal UMP-residues found in newly transcribed U6 snRNA. Not involved in replication-dependent histone mRNA degradation.^{[1] [2] [3]}

References

1. ↑ Trippe R, Guschina E, Hossbach M, Urlaub H, Luhrmann R, Benecke BJ. Identification, cloning, and functional analysis of the human U6 snRNA-specific terminal uridylyl transferase. RNA. 2006 Aug;12(8):1494-504. Epub 2006 Jun 21. PMID:16790842 doi:http://dx.doi.org/rna.87706
2. ↑ Mellman DL, Gonzales ML, Song C, Barlow CA, Wang P, Kendziorski C, Anderson RA. A PtdIns4,5P2-regulated nuclear poly(A) polymerase controls expression of select mRNAs. Nature. 2008 Feb 21;451(7181):1013-7. doi: 10.1038/nature06666. PMID:18288197 doi:http://dx.doi.org/10.1038/nature06666
3. ↑ Laishram RS, Anderson RA. The poly A polymerase Star-PAP controls 3'-end cleavage by promoting CPSF interaction and specificity toward the pre-mRNA. EMBO J. 2010 Dec 15;29(24):4132-45. doi: 10.1038/emboj.2010.287. Epub 2010 Nov, 19. PMID:21102410 doi:http://dx.doi.org/10.1038/emboj.2010.287