title: Evidence for a secretory pathway Ca2+-ATPase in sea urchin spermatozoa.
abstract: Plasma membrane, sarco-endoplasmic reticulum and secretory pathway Ca2+-ATPases (designated PMCA, SERCA and SPCA) regulate intracellular Ca2+ in animal cells. The presence of PMCA, and the absence of SERCA, in sea urchin sperm is known. By using inhibitors of Ca2+-ATPases, we now show the presence of SPCA and Ca2+ store in sea urchin sperm, which refills by SPCA-type pumps. Immunofluorescence shows SPCA localizes to the mitochondrion. Ca2+ measurements reveal that approximately 75% of Ca2+ extrusion is by Ca2+ ATPases and 25% by Na+ dependent Ca2+ exchanger/s. Bisphenol, a Ca2+ ATPase inhibitor, completely blocks the acrosome reaction, indicating the importance of Ca2+-ATPases in fertilization.
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202, USA. hgunarat@ucsd.edu
authors.forename: Herath Jayantha
authors.initials: HJ
authors.lastname: Gunaratne
authors.forename: Victor D
authors.initials: VD
authors.lastname: Vacquier
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008969:Molecular Sequence Data; D010636:Phenols / Q000494:pharmacology; D012617:Sea Urchins / Q000201:enzymology*; D016415:Sequence Alignment; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D013094:Spermatozoa / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D010636:Phenols; D019831:Sodium-Calcium Exchanger; C074530:potassium-dependent sodium-calcium exchanger; C403624:ATP2C1 protein, human; D000252:Calcium-Transporting ATPases; D002118:Calcium