Ca-ATPase activity in the rabbit and bovine lens.
Membrane-rich vesicle preparations of rabbit and bovine lenses were prepared in such a manner as to preserve ATPase activity. The lipid:protein ratio of these preparations was increased 22- to 33-fold with a 94% recovery of total phospholipid. Using this preparation, calcium stimulated ATPase was routinely determined in both individual lenses and in pooled specimens. The pattern of stimulation of ATPase activity by a range of calcium concentrations was found to be similar in membrane preparations of epithelium and cortex, from rabbit and bovine lenses. The concentration of calcium necessary for half-maximal stimulation of ATPase activity was approximately 10(-6) M. Calcium concentrations in excess of 10(-4) M reduced the ATPase activity. Calcium-ATPase was undetectable in the lens nuclear region of both species. The regional distribution of sodium-potassium ATPase was also measured.
Borchman
D
D
Department of Ophthalmology, University of Louisville School of Medicine, Kentucky Lions Eye Research Institute 40202.
Delamere
N A
NA
Paterson
C A
CA
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002417:Cattle / Q000378:metabolism*; D007903:Lens Capsule, Crystalline / Q000201:enzymology; D007908:Lens, Crystalline / Q000201:enzymology* / Q000648:ultrastructure; D008566:Membranes / Q000201:enzymology / Q000648:ultrastructure; D008722:Methods; D009994:Osmolar Concentration; D011817:Rabbits / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium