Calcium/calmodulin-regulated and magnesium-dependent enzyme that catalyzes the hydrolysis of ATP coupled with the transport of calcium out of the cell (By similarity). By regulating sperm cells calcium homeostasis, may play a role in sperm motility (By similarity). ATP + Ca(2+)(in) + H2O = ADP + Ca(2+)(out) + H(+) + phosphate Activated by calcium/calmodulin. Interacts with PDZD11. Interacts with SLC35G1 and STIM1. Interacts with calmodulin. Isoform 1 is detected in brain, heart, liver, testis and epididymis. Isoform 2 is detected in brain (at protein level), heart, seminal vesicle and epididymis. There is a shift in expression from isoform 1 to isoform 2 along the length of the epididymis from caput to cauda (at protein level). Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IIB subfamily.