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Localization and properties of a high‐affinity (Ca 2+ + Mg 2+ )‐ATPase in isolated kidney cortex plasma membranes
Author(s) -
Gmaj Pitro,
Murer Heini,
Carafoli Ernesto
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)80643-1
Subject(s) - citation , library science , chemistry , computer science
Two different calcium-transport systems have been found to operate in parallel in kidney basal-lateral plasma membranes: an ATP-dependent Ca*+-transport and a Na+/Ca*+ exchange [I]. It was suggested that a high-affinity Ca*+-ATPase was involved in the ATP-dependent Ca*+ uptake by inverted basal-lateral membrane vesicles, and thus in the extrusion of Ca*+ from the tubular cell in vivo. However, very little is known about the enzyme itself. Kinne Safran and Kinne [2] found a low-affinity Ca* + -ATPase activity in kidney basal-lateral membranes. De Smedt et al. [3] reported a partial purification of a high-affinity, calmodulin-dependent (Ca*+ + Mg*+)-ATPase from kidney cortex microsomes, but the origin of the enzyme was not established in [3]. Van OS et al. [4] reported in an abstract the presence of a Ca*+-stimulated ATPase with high affinity for calcium (Kmca2+ 0.4 PM) in a basal-lateral plasma membrane fraction from the kidney. Here, we report the localization, kinetics, calmodulin dependence and inhibitor sensitivity of a high-affinity (Ca*+ + Mg*+)ATPase in highly purified basal-lateral plasma membranes from rat kidney cortex.