Two protein-protein interaction sites on the spliceosome-associated human cyclophilin CypH.

ABSTRACT: Cyclophilins are a family of proteins that share a common, highly conserved sequence motif. Cyclophilins bind transiently to other proteins and facilitate their folding. One member of the family, hCypH, is part of the human spliceosomal [U4/U6.U5] tri-snRNP complex; it associates specifically and stably with the U4/U6-specific protein 60K. Here, we demonstrate that recombinant hCypH exhibits peptidyl-prolyl isomerase (PPIase) activity, and describe mutagenesis studies demonstrating that it shares the catalytic pocket with other members of the cyclophilin family. However, neither the PPIase activity nor the catalytic pocket is required for binding of protein 60K. Rather, hCypH contains a small insertion in a loop of the otherwise conserved cyclophilin backbone, and this minor change creates

SUBMITTER: Ingelfinger D 

PROVIDER: S-EPMC169899 | biostudies-literature | 2003 Aug

REPOSITORIES: biostudies-literature