Phosphorylation of proteins of skeletal muscle sarcoplasmic reticulum of the ground squirrel Spermophilus undulatus by endogenous protein kinasesстатья
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Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:An endogenous protein kinase activity was found in membrane preparations of sarcoplasmic reticulum isolated from skeletal muscles of summer active and winter hibernating ground squirrel Spermophilus undulatus. Sarcoplasmic reticulum proteins are the targets for endogenous protein kinases; the level of (32)p incorporation is 175 +/- 25 and 195 +/- 15 pmol/mg of protein for preparations from summer active and winter hibernating animals, respectively. The activators of protein kinase A (cAMP) and protein kinase G (cGMP) do not significantly affect protein phosphorylation but Ca2+ in micromolar concentrations (alone or in the presence of calmodulin) decreases 3-4-fold the level of phosphate incorporation into sarcoplasmic reticulum proteins of both summer active and winter hibernating ground squirrels. Solubilization of sarcoplasmic reticulum membranes by nonionic detergent Triton X-100 increases 3-fold and 5-fold the level of phosphate incorporation into proteins of preparations from summer active and winter hibernating animals, respectively. The inhibitor of casein kinase, heparin, does not affect phosphorylation of proteins in intact membrane preparations of sarcoplasmic reticulum but totally prevents the stimulation of protein phosphorylation by Triton X-100. It is concluded that endogenous protein kinases are located in reticulum lumen and that casein kinase dominates among endogenous protein kinases presented in sarcoplasmic reticulum of the ground squirrel.