骨骼肌内质网Ca2+泵转运Ca2+的结构基础

Ca²⁺泵(Ca²⁺-ATPase)是调节细胞内Ca²⁺浓度的重要蛋白质之一. Ca²⁺泵在转运Ca²⁺的过程中经历一系列构象变化. 其中，E1状态为外向的Ca²⁺高亲和状态，E2状态则为内向的Ca²⁺低亲和状态. 目前，骨骼肌内质网Ca²⁺泵转运Ca²⁺过程中的几个中间状态，包括E1-2Ca²⁺，E1-ATP，E1-P-ADP，E2-Pi和E2状态的三维晶体结构已经解析. 介绍这几种状态的晶体结构，并分析Ca²⁺泵在执行功能过程中结构与功能的关系.

The Structural Basis of Ca2+ Transport by The Ca2+-ATPase From Skeletal Sarcoplasmic Reticulum

The Ca²⁺-ATPase of sarcoplasmic reticulum is a Ca²⁺ pump that plays a key role in regulating cytosol calcium concentration in muscle cells. It undergoes a sequential conformational transition during the transport process. According to the classical E1/E2 theory, in the E1 state the binding sites have high affinity and open to the cytoplasm, whereas in the E2 state the binding sites have low affinity and face the luminal side. Crystal structures of several states during the reaction cycle of Ca²⁺-ATPase have been solved recently, including a Ca²⁺-bound form (E1-2Ca²⁺), a Ca²⁺-unbound form stabilized by a potent inhibitor thapsigargin (TG) (E2-TG), an ATP-bound form (E1-ATP), an E1-P-ADP state, and an E2-Pi state. The details of these crystal structures and the relationship between structure and function of Ca²⁺-ATPase during reaction cycle were summarized, and the issues to be addressed in future research were raised.