Characteristics of Ca2+/calmodulin- and Ca2+/phosphatidylserine-stimulated phosphoproteins in rat striatum.
The characteristics of endogenous Ca2+/calmodulin (CaM)- and Ca2+/phosphatidylserine (PS)-stimulated phosphorylated proteins in the striatum of rat were partially determined and compared in this study. The Ca2+/CaM-dependent phosphoproteins were associated with serine and threonine residues. The sensitivity of these proteins for phosphorylation by Ca2+/CaM was not affected by pretreatment of tissue with Ca2+ chelating agent, EGTA or with non-ionic detergent, Triton X-114. Triton X-114 phase separation experiments revealed that these Ca2+/CaM-dependent phosphoproteins were partitioned in the detergent rich phase suggesting that they are integral proteins of the striatal membrane. On the other hand, the Ca2+/PS-dependent phosphorylated proteins were primarily associated with the serine residue. Phosphorylation of these proteins by Ca2+/PS were abolished after the treatment with EGTA or Triton X-114. These results suggest that Ca2+/PS-dependent striatal phosphoproteins are biochemically unstable in maintaining their state of phosphorylation.
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Department of Pharmacology, Creighton University Medical School, Omaha, Nebraska 68178-0225.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003342:Corpus Striatum / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D008297:Male; D017830:Octoxynol; D010718:Phosphatidylserines / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D002147:Calmodulin; D010718:Phosphatidylserines; D010750:Phosphoproteins; D010769:Phosphothreonine; D010768:Phosphoserine; D011092:Polyethylene Glycols; D004533:Egtazic Acid; D017830:Octoxynol; C010615:Nonidet P-40; D002118:Calcium