Peptidyl-prolyl cis-trans isomerase H is an enzyme that in humans is encoded by the PPIHgene.
The protein encoded by this gene is a member of the peptidyl-prolyl cis-trans isomerase (PPIase) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and accelerate the folding of proteins. This protein is a specific component of the complex that includes pre-mRNA processing factors PRPF3, PRPF4, and PRPF18, as well as U4/U5/U6 tri-snRNP. This protein has been shown to possess PPIase activity and may act as a protein chaperone that mediates the interactions between different proteins inside the spliceosome.
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Reidt U, Wahl MC, Fasshauer D, et al. (2003). "Crystal structure of a complex between human spliceosomal cyclophilin H and a U4/U6 snRNP-60K peptide". J. Mol. Biol. 331 (1): 45–56. doi:10.1016/S0022-2836(03)00684-3. PMID12875835.