High affinity ryanodine binding sites in rat liver endoplasmic reticulum.
The binding of [3H]ryanodine to liver microsomal subfractions was investigated. The smooth microsomal membranes were enriched with ryanodine binding sites and also with a polypeptide of 360 kDa. Caffeine completely inhibited [3H]ryanodine binding. Ryanodine also affected the membrane Ca2+ permeability. At low concentrations (less than 10 microM) ryanodine stimulated Ca2+ efflux and at higher concentrations (greater than 50 microM) it blocked Ca2+ efflux. These results suggest that hepatic microsomes contain ryanodine binding sites which can modify the membrane permeability for Ca2+.
Shoshan-Barmatz
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Department of Biology, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
D000470:Alkaloids / Q000378:metabolism*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000378:metabolism*; D012433:Ryanodine / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel
D000470:Alkaloids; D011950:Receptors, Cholinergic; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002110:Caffeine; D002118:Calcium