The type 2C Ser/Thr phosphatase PP2Cgamma is a pre-mRNA splicing factor

摘要: To identify activities involved in human pre-mRNA splicing, we have developed a procedure to separate HeLa cell nuclear extract into five complementing fractions. An activity called SCF1 was purified from one of these fractions by assaying for reconstitution splicing the presence remaining four A component is shown be PP2Cγ, type 2C Ser/Thr phosphatase previously unknown function. Previous work suggested that dephosphorylation factors may important catalysis after spliceosome assembly, although identities specific phosphatases remain unclear. Here show PP2Cγ physically associated with vitro throughout reaction, but first required during early stages assembly efficient formation complex. The function as an active site mutant does not support assembly. requirement highly specific, closely related PP2Cα cannot substitute PP2Cγ. Consistent role localizes nucleus vivo. We conclude at least event catalyzed spliceosome.