A NUCLEAR RNA-BINDING CYCLOPHILIN IN HUMAN T-CELLS

Cyclophilins (CyPs) are binding proteins for the immunosuppressive dru g cyclosporin A (CsA). CyPs are evolutionarily highly conserved protei ns present in both pro- and eukaryotes as well as in different subcell ular locations. CyPs possess enzymatic activity, namely peptidyl-proly l cis-trans isomerase (PPIase) activity; CyPs are involved in cellular protein folding and protein interactions. To date, only cyclosporins and proteins are known to interact with CyPs. Here we describe a novel nuclear cyclophilin (hCyP33) from human T cells with an additional RN A-binding domain. This combines for the first time RNA binding and pro tein folding in one protein.