A calmodulin-stimulated Ca2+-ATPase from plant vacuolar membranes with a putative regulatory domain at its N-terminus

A cDNA, BCA1, encoding a calmodulin-stimulated Ca2+-ATPase in the vacuolar membrane of cauliflower (Brassica oleracea) was isolated based on the sequence of tryptic peptides derived from the purified protein. The BCA1 cDNA shares sequence identity with animal plasma membrane Ca2+-ATPases and Arabidopsis thaliana ACA1, that encodes a putative Ca2+ pump in the chloroplast envelope. In contrast to the plasma membrane Ca2+-ATPases of animal cells, which have a calmodulin-binding domain situated in the carboxy-terminal end of the molecule, the calmodulin-binding domain of BCA1 is situated at the amino terminus of the enzyme.