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High‐affinity Ca 2+ ‐binding site inhibiting Ca 2+ release from sarcoplasmic reticulum
Author(s) -
Argaman Anat,
Shoshan-Barmatz Varda
Publication year - 1989
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(89)81223-2
Subject(s) - egta , divalent , endoplasmic reticulum , chemistry , calcium , membrane , biophysics , binding site , nuclear chemistry , biochemistry , biology , organic chemistry
Ca 2+ release from sarcoplasmic reticulum membranes, activated by alkaline pH occurs only when EGTA is present in the release medium. Addition of very low concentrations of Ca 2+ to the medium inhibits Ca 2+ release. The concentration of free Ca 2+ required for 50% inhibition ranges from between 5 and 20 nM in different experiments and/or membrane preparations, irrespective of whether the free Ca 2+ concentration is controlled by EGTA or CDTA. Other divalent cations such as Mn 2+ , Ba 2+ , Cu 2+ , Cd 2+ and Mg 2+ also exert an inhibitory effect on Ca 2+ release, with higher or lower potency than that of Ca 2+ . The inactivation of Ca 2+ release by Ca 2+ is reversible. We suggest the involvement of high‐affinity Ca 2+ ‐binding sites in the control of Ca 2+ release.