Structure and function of the calcium pump protein of sarcoplasmic reticulum.

Recent developments concerning the structure and function of the Ca2+ pump protein of the sarcoplasmic reticulum have been briefly reviewed. Various new methods have become available that make it possible to monitor dynamic changes in the structure of the enzyme molecule associated with elementary steps of the enzyme reaction. In the light of information about chemical reactivity of various amino acid residues and their location in the primary structure of the ATPase polypeptide, it will be fruitful to use extrinsic conformational probes placed at specific locations to monitor the kinetics of the enzyme. Furthermore, a growing body of evidence suggests that subunit-subunit interactions of an oligomeric Ca2+ ATPase are involved in the regulation of the kinetics of the enzyme. Thus the kinetic mechanisms has to be reinterpreted at all levels--i.e. primary, secondary, tertiary, and quaternary--of structure.