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Potentiating effect of calmodulin and catalytic subunit of cyclic AMP‐dependent protein kinase on ATP‐dependent Ca 2+ ‐transport by cardiac sarcolemma
Author(s) -
Vetter Roland,
Haase Hannelore,
Will Horst
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)80834-x
Subject(s) - sarcolemma , calmodulin , protein subunit , protein kinase a , chemistry , membrane , biophysics , biochemistry , membrane transport , enzyme , biology , gene
Highly purified sarcolemmal membranes were prepared from pig heart homogenates by differential and density gradient centrifugations. The membrane fragments exhibit ATP‐dependent Ca 2+ ‐transport and Na + /Ca 2+ ‐exchange activities. ATP‐dependent Ca 2+ ‐transport ( K Ca 2+ 0.5 = 0.3 μM; V max = 4.6 nmol Ca 2+ •mg protein −1 •min −1 )_is not stimulated by oxalate. Ca 2+ ‐uptake is also not supported by p ‐nitrophenylphosphate. Preincubation of sarcolemma with MgATP, calmodulin and catalytic subunit of cyclic AMP‐dependent protein kinase stimulates active Ca 2+ ‐transport 1.8‐fold. The effects of calmodulin and catalytic subunit are potentiating rather than additive. A large portion of the Ca 2+ additionally accumulated after prephosphorylation of membranes is exchangable for Na + via the Na + /Ca 2+ ‐exchange system.