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RNA. 1997 Dec;3(12):1374-87.

A new cyclophilin and the human homologues of yeast Prp3 and Prp4 form a complex associated with U4/U6 snRNPs.

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1
Cold Spring Harbor Laboratory, New York 11724, USA. dhorowit@mx3.usuhs.mil

Abstract

We have purified three new human U4/U6-snRNP proteins from HeLa cells. The three proteins formed a tightly bound complex and behaved as a single species throughout the purification. All three proteins have been identified by peptide sequencing, and full-length cDNA sequences have been obtained for all of them. Two of the proteins are homologues of the Saccharomyces cerevisiae splicing factors Prp3 and Prp4, and the third protein is a cyclophilin. Both the human and S. cerevisiae Prp4 proteins have seven repeats of the WD motif and likely fold into structures very similar to those of the beta subunits of G proteins. The human Prp3 protein is highly basic and is closely related to S. cerevisiae Prp3 only in its carboxyl-terminal half. The human homologues of Prp3 and Prp4 are part of a stable complex in the absence of RNA. The third protein in the complex is a new cyclophilin. Cyclophilins have been proposed to act as chaperones in a variety of cellular processes, and we discuss some possible roles of this U4/U6 snRNP-associated cyclophilin.

PMID:
9404889
PMCID:
PMC1369579
[Indexed for MEDLINE]
Free PMC Article

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