High-affinity Ca 2+-binding site inhibiting Ca 2+ release from sarcoplasmic reticulum

• Published in: FEBS letters Vol. 243; no. 1; pp. 88 - 92
• Main Authors: Argaman, Anat, Shoshan-Barmatz, Varda
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 16.01.1989
• Subjects: Ca 2+ release; Sarcoplasmic reticulum; Tricine, N-[2-hydroxy-1,1-bis-(hydroxy-methyl)ethyl]glycine Mops, 3-( N-morpholino)propanesulfonic acid; Sarcoplasmic reticulum; SR, sarcoplasmic reticulum; RR, ruthenium red; TPB −, tetraphenylboron; CDTA, trans-1,2-diamino-cyclohexane- N, N, N′, N′-tetraacetic acid; Ca 2+ release; DCCD, N, N′-dicyclohexyl carbodiimide
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(89)81223-2

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.