Ca2+-ATPase activity in the human lens.
A membrane-rich preparation of paired human lenses was prepared in such a manner as to preserve ATPase activity. The lipid:protein ratio of these preparations was increased 12-fold with an 85% recovery of total phospholipid. 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. The concentration of calcium necessary for half-maximal simulations of ATPase activity was approximately 10(-6) M. Ca2+-ATPase activity is undetectable in the lens nuclear region. A shift in the sensitivity of lens epithelial Ca2+-ATPase activity was observed with increasing age concomitant with a general increase in Ca2+-ATPase activity suggesting age related modifications of the membrane.
Borchman
D
D
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Kentucky.
Paterson
C A
CA
Delamere
N A
NA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000032:analysis* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003459:Crystallins / Q000378:metabolism; D004848:Epithelium / Q000201:enzymology; D006801:Humans; D007223:Infant; D007908:Lens, Crystalline / Q000032:analysis* / Q000201:enzymology / Q000378:metabolism; D050356:Lipid Metabolism; D008875:Middle Aged; D010743:Phospholipids / Q000378:metabolism
D003459:Crystallins; D010743:Phospholipids; D000252:Calcium-Transporting ATPases; D002118:Calcium