科研之友
微信
新浪微博
Facebook
分享链接
摘要
Recycling of G protein-coupled receptors determines the functional resensitization of receptors and is implicated in switching beta(2) adrenoceptor (beta(2)AR) G protein specificity in cardiomyocytes. The human beta(2)AR carboxyl end binds to the N-ethylmaleimide-sensitive factor (NSF), an ATPase integral to membrane trafficking machinery. It is interesting that the human beta(2)AR (h beta(2)AR) carboxyl end pulled down NSF from mouse heart lysates, whereas the murine one did not. Despite this difference, both beta(2)ARs exhibited substantial agonist-induced internalization, recycling, and G(i) coupling in cardiomyocytes. The h beta(2)AR, however, displayed faster rates of agonist-induced internalization and recycling compared with the murine beta(2)AR (m beta(2)AR) and a more profound G(i) component in its contraction response. Replacing the m beta(2)AR proline (-1) with a leucine generated a gain-of-function mutation, m beta(2)AR-P417L, with a rescued ability to bind NSF, faster internalization and recycling than the m beta(2)AR, and a significant enhancement in G(i) signaling, which mimics the h beta(2)AR. Selective disruption of the m beta(2)AR-P417L binding to NSF inhibited the receptor coupling to G(i). Meanwhile, inhibiting NSF with N-ethylmaleimide blocked the m beta(2)AR recycling after agonist-induced endocytosis. Expressing the NSF-E329Q mutant lacking ATPase activity inhibited the m beta(2)AR coupling to G(i) in cardiomyocytes. Our results revealed a dual regulation on h beta(2)AR trafficking and signaling by NSF through direct binding to cargo receptor and its ATPase activity and uncovered an unprecedented role for the receptor binding to NSF in regulating G protein specificity that has diverged between mouse and human beta(2)ARs.
- 出版日期2007-8
