Calcium transport in inside-out membrane vesicles prepared from rabbit neutrophils.
Inside-out membrane vesicles capable in the presence of MgATP of accumulating calcium and containing Ca2+-ATPase activity have been prepared from rabbit neutrophils. The transport system has a Km for Ca2+ of 2.8 +/- 0.3 microM and a Vmax of 5.3 +/- 0.3 nmol/mg of protein . min and a Km for ATP of 0.35 +/- 0.13 mM and a Vmax of 5.8 +/- 0.3 nmol/mg protein . min. The Ca2+-activated ATPase system has a Km for Ca2+ of 0.2 +/- 0.05 microM and a Vmax of 4.0 +/- 0.5 nmol/mg protein . min, and a Km for ATP of 0.36 +/- 0.2 mM and a Vmax of 5.0 +/- 0.6 nmol/mg protein . min. It was also found that neither these inside-out vesicles nor the intact rabbit neutrophils contain a Na+/Ca2+ exchange mechanism.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000097:blood*; D000252:Calcium-Transporting ATPases / Q000097:blood*; D002462:Cell Membrane / Q000201:enzymology; D007700:Kinetics; D009504:Neutrophils / Q000201:enzymology*; D010587:Phagocytosis; D011817:Rabbits
D000252:Calcium-Transporting ATPases; D002118:Calcium