Structure of the Calcium Transporter Proteins in Matrix Vesicles

Structure of the Calcium Transporter Proteins in Matrix Vesicles 

The annexins bind to phospholipids in a reversible Ca2+-dependent manner. They are implicated in membrane fusion, vesicular trafficking, and ion-channel formation. X-ray crystal structures of various soluble annexins all reveal a common backbone fold in which each of four repeats in the core domain contains five a-helices connected by short loops (Fig. 9.6a). Two of these loops come together to form Ca2+-binding sites that coordinate with the negatively charged head-group of phosphatidylserine on the cytosolic surface of membranes. Unfortunately, this association does not explain its ion-channel activity. That 

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