DISSECTION OF THE FUNCTIONAL DOMAINS OF THE SARCOPLASMIC-RETICULUM CA2-ATPASE BY SITE-DIRECTED MUTAGENESIS()

The results of site-directed mutagenesis studies of the sarcoplasmic r eticulum Ca2+-ATPase are reviewed. More than 250 different point mutan ts have been expressed in cell culture and analysed by a panel of func tional assays. Thereby, 40-50 important amino acid residues have been pinpointed, and the mutants have been assigned to functional classes: the Ca2+-affinity mutants, the phosphorylation-negative mutants, the A TP-affinity mutants, the E(1)P mutants, the E(2)P mutants, and the unc oupled mutants. Moreover, regions important to the specific inhibition by thapsigargin have been identified by analysis of Ca2+-ATPase/Na+, K+-ATPase chimeric constructs.