摘要
Objective:Cyclophilin A (Cyp A) is a ubiquitously distributed protein belonging to the immunophilin family and is recognized as the host cell receptor for the potent immunosuppressive
Objective： Cyclophilin A （Cyp A） is a ubiquitously distributed protein belonging to the immunophilin family and is recognized as the host cell receptor for the potent immunosuppressive drug cyclosporine A （CsA）. The Na^＋/Ca^2＋ exchanger （NCX） is a major regulator for cytoplasmic calcium expressed in the cell surface membrane of all excitable and many non-excitable tissues. It was reported that Cyp A is involved in NCX1 protein expression in HEK 293 cells and its modulation by CsA. Methods： Here the authors investigated the effect of the human Cyp A （HCyp A） on NCXlheterologously expressed in Xenopus oocytes. The electrogenic current generated by NCX1 was measured under voltage-clamp and taken as a measure for the activity of the transporter. Results： In the reversed mode, NCX1 transports 3 Na^＋ ions out of the cell and 1 Ca^2＋ ion into the cell. Intracellularly applied Homo sapiens Cyp A （HCyp A） does not affect NCX1-mediated current, but extracellularly applied HCyp A stimulated the NCX1-dependent current at positive potentials.
基金
the Science Foundation of Shanghai Municipal Commission of Science and Technology(05DZ19745,06DZ19732,064319053,07DZ19722,07DZ19733)
the National Basic Research Program of China(973 Program,2005CB523306)
Shanghai Leading Academic Discipline Project(B112 and T0302)
