Identification of the site phosphorylated by casein kinase II in smooth muscle caldesmon |
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Authors: | A Wawrzynow J H Collins N V Bogatcheva A V Vorotnikov N B Gusev |
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Institution: | Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201. |
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Abstract: | Phosphorylation of avian gizzard caldesmon by casein kinase II was investigated. The enzyme incorporates about 1 mol of phosphate per mol of caldesmon. All sites of phosphorylation are located in short chymotryptic peptides with Mr 25-27 kDa or in the short N-terminal peptide formed after cleavage of chicken gizzard caldesmon at Cys153. The primary structure of the tryptic peptide containing the main site of duck gizzard caldesmon phosphorylation is S-E-V-N-A-Q-N-X-V-A-E-D-E-T-K, where X is an unidentified residue, presumed to be phosphoserine. Thus, Ser73 is the main site phosphorylated by casein kinase II in avian gizzard caldesmon. |
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