Unique calcium-dependent hydrophobic binding proteins: possible independent mediators of intracellular calcium distinct from calmodulin.
Calcium-dependent regulation of cellular processes is mediated by specific intracellular proteins. A newly described set of proteins isolated from chicken gizzard with Mr of 67 X 10(3), 35 X 10(3), 33 X 10(3) and 30 X 10(3) also express a hydrophobic site in the presence of calcium. These proteins are isolated from several other cellular tissues and are termed calcimedins. These proteins differ from calmodulin in isoelectric point, DEAE-cellulose binding characteristics and heat stability. The calcimedins do not activate calmodulin-dependent cyclic nucleotide phosphodiesterase but do activate a hepatic microsomal Ca2+ -ATPase system. Hence, the possibility is opened that calcium regulation of cellular processes is mediated by calcium-binding proteins in addition to calmodulin.
D000818:Animals; D017302:Annexins; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D002645:Chickens; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D008862:Microsomes, Liver / Q000201:enzymology; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000378:metabolism; D014867:Water / Q000378:metabolism
D017302:Annexins; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D014867:Water; D000252:Calcium-Transporting ATPases; D002118:Calcium