Hormonal regulation of thyroidal protein phosphokinase activities

Increased cyclic AMP‐independent protein kinase activity in thyroid toxic adenomas

“…An increased activity of both enzymes after chronic treatment of rats by TSH was reported [13]. It is interesting to note that in TA, despite the low levels of circulating TSH, only the cAMP-independent PKA was clearly elevated.…”

“…The presence in the thyroid tissue of both cAMPdependent and -independent PKAs has been documented [11][12][13]. An increased activity of both enzymes after chronic treatment of rats by TSH was reported [13].…”

Altered ratios and different subcellular distribution of type I and type II cAMP‐dependent protein kinases in several thyroidal pathological tissues

“…All other techniques (cytosol fractionation and protein kinase determination) have been described in [6,27]. Results are expressed either in % of total activity determined for each type of tissue (pmol 32P incorporated into histone/mg tissue in 5 min incubation), or relatively, with respect to control tissue (normal glands).…”

Heterogeneity of the catalytic activity arising from thyroidal cAMP‐dependent protein kinase type II

“…Under these conditions thyroidal cAMP-dependent protein kinases were recovered in 2 peaks: type I kinase corresponds to peak 1 which sediments at 4.9 S; type II kinase corresponds to peak 2, which sediments at 6.2 S [ 18,20]. For the estimation of sedimentation coefficients, myoglobin (S2o,w = 2) and glucose-oxidase (S2o,w = 7.93) were used as internal markers.…”

“…Since we have found that rat thyroid cytosol contains a substantial amount of cAMP-independent histone kinase [20], we estimated both cAMP-dependent and cAMP-independent activities in parallel throughout this study. Cyclic AMP-independent histone kinase activity was evaluated inthe presence of the heat-stable inhibitor of cAMP-dependent enzymes [21 ] which was prepared in the laboratory from hog or sheep brains and purified up to the Sephadex G-75 filtration step [22].…”