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Catalytic domain of the Serine/Threonine Kinase, Pre-mRNA-Processing factor 4 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PRP4 phosphorylates a number of factors involved in the formation of active spliceosomes, which catalyze pre-mRNA splicing. It phosphorylates PRP6 and PRP31, components of the U4/U6-U5 tri-small nuclear ribonucleoprotein (snRNP), during spliceosomal complex formation. In fission yeast, PRP4 phosphorylates the splicing factor PRP1 (U5-102 kD in mammals). Thus, PRP4 plays a key role in regulating spliceosome assembly and pre-mRNA splicing. It also plays an important role in mitosis by acting as a spindle assembly checkpoint kinase that is required for chromosome alignment and the recruitment of the checkpoint proteins MPS1, MAD1, and MAD2 at kinetochores. The PRP4 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",