High resolution

Module 5: Figure PMCA domain structure

Domain structure of the plasma membrane Ca2+-ATPase (PMCA).

A. The sites marked A and C are the main sites where alternative splicing occurs to create at least 20 different isoforms. These two splice sites occur in the two large cytoplasmic loops, and are thus likely to influence the way in which these two loops regulate pump activity. B. In the absence of calmodulin (CaM), the autoinhibitory C-terminal region is thought to bend around to inhibit enzymatic activity. In the presence of Ca2+, CaM binds to the CaM-binding domain (CaMBD), and this regulatory chain is pulled away, resulting in an increase in pump activity. Reproduced from Strehler, E.E. and Zacharias, D.A. (2001) Role of alternative splicing in generating isoform diversity among plasma membrane calcium pumps. Physiol. Rev. 81:21–50; used with permission from The American Physiological Society; see Strehler and Zacharias 2001.