The effect of insulin and guanosine nucleotides on protein phosphorylations by sarcolemma membranes from skeletal muscle.

In a previous report we have shown that insulin increases the phosphorylation of an endogenous protein of mol. wt. 16 000 daltons in sarcolemma membranes.

Effect of epinephrine and insulin on adenosine 3'5'-cyclic monophosphate--dependent protein kinase in human skeletal muscle in vivo.

Cyclic AMP dependent protein kinase has beeen identified in human skeletal muscle tissue. In crude muscle extracts the enzyme was 3--5 fold activated by cyclic AMP. The cyclic AMP-dependent activity (corresponding to the inactive holoenzyme) was completely inhibited by the heat stable inhibitor of protein kinase.

Effect of thyroliberin on the concentration of adenosine 3':5'-phosphate and on the activity of adenosine 3':5'-phosphate-dependent protein kinase in prolactin-producing cells in culture.

1. The effects of thyroliberin were studied in cultured rat pituitary-tumour cells that synthesize and secrete prolactin (the GH4C1 cell strain). 2.