Isoproterenol phosphorylation activation

Additional information <1, 3, 7> (<3> agonists induce specific conformational changes allowing phosphorylation [7] <3> partial agonists promote reduced receptor phosphorylation [8] <1> not activated by cAMP, cGMP, Ca /calmodulin, Ca /phospholipid, phorbol esters [1] <3> ctz-AR phosphorylation is not stimulated by isoproterenol [2] <3> not effected by Ca "... 

The biochemical mechanisms by which cAMP-dependent phosphorylation leads to enhanced IR-PTH release remain to be determined. It is of interest, however, that isoproterenol activates phosphorylation of proteins of similar molecular weight in the rat parotid gland (22), while glucagon stimulates phosphorylation of a protein of molecular weight 19,000 in calcitonin-secreting cultured cells from a medullary carcinoma of the rat thyroid (22) It is conceivable that in all three tissues, activation of exocytosis results from a cAMP-dependent phosphorylation of a critical cellular substrate. 

Holm, Identification of novel phosphorylation sites in hormone-sensitive lipase that are phosphorylated in response to isoproterenol and govern activation properties in vitro, J. Biol. Chem., 1998, 273, 215-221. 

The opening and closing of L-type calcium channels is controlled by the membrane potential. In addition, the p-adrenergic receptor controls the availability of the channel to open upon membrane depolarization. Isoproterenol increases the cardiac calcium current three- to sevenfold either by cAMP-dependent phosphorylation of the channel (Kameyama et al., 1985 Hartzell and Fischmeister, 1992) or by the activated a subunits of the trimeric GTP binding protein Gs (Yatani and Brown, 1989) or by a combination of the activated a subunits of the trimeric GTP binding protein Gg and the active cAMP kinase (Cavalie et al.,... 

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