Phosphorylative neuromodulation of the regulatory subunit of cyclic AMP-dependent protein kinase type II in skeletal muscle.
The phosphorylative neuromodulation of the regulatory subunit of protein kinase type II (R-II) in cytosolic fractions from denervated and sham-operated, contralateral soleus muscles of the rat was evaluated. The denervation-induced increase in the 32P-phosphorylation of R-II is not related to an increased dephosphorylation by cation-dependent or cation-independent protein phosphatases in the cytosolic fractions. The level of 32P-phosphorylation of an exogenous heptapeptide substrate (Kemptide) by dissociated catalytic subunits of cyclic AMP-dependent protein kinase in cytosolic fractions from denervated and sham-operated solei did not differ. Also, no change in the concentration of cytosolic R-II assessed by competitive enzyme-linked immunosorbent assays (ELISA) was found after denervation. However, the in vitro 32P-phosphorylation of R-II in these samples was increased. Taken together, our results suggest that the increased availability of autophosphorylatable sites reflects an in vivo modulation of R-II phosphorylation rather than a significant change in total R-II content.
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D003714:Denervation; D047908:Intracellular Signaling Peptides and Proteins; D008970:Molecular Weight; D009132:Muscles / Q000294:innervation* / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013997:Time Factors
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C015482:protein kinase modulator; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases