title: Hyperthyroidism affects the activity of a cAMP-dependent protein kinase and protein phosphorylation in heart sarcolemma.
abstract: We have investigated the effect of thyroxine administration on the cAMP related systems in heart sarcolemma. Hyperthyroidism produces an increase in the number of beta-receptors and enhances in situ the phosphorylation of some sarcolemmal proteins, in particular the 55 kDa peptide. On the other hand, the activity of a membrane-bound cAMP-dependent protein kinase is considerably lower in sarcolemma obtained from animals receiving the hormone. We suggest that the thyroxine-induced alteration in beta-receptors elevates the content of cAMP in the cell which, in turn, evokes a transient dissociation of the catalytic subunit of a cAMP-dependent kinase from the regulatory subunit embeded in the membrane.
authors.affiliation: Nencki Institute of Experimental Biology, Department of Muscle Biochemistry, Warsaw, Poland.
authors.forename: K S
authors.initials: KS
authors.lastname: Famulski
authors.forename: G
authors.initials: G
authors.lastname: Szymańska
authors.forename: P
authors.initials: P
authors.lastname: Szymański
authors.forename: M G
authors.initials: MG
authors.lastname: Sarzała
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D006980:Hyperthyroidism / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012508:Sarcolemma / Q000378:metabolism; D013974:Thyroxine / Q000494:pharmacology
chemical_list: D011506:Proteins; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D011494:Protein Kinases; D013974:Thyroxine