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Activation of phosphorylase kinase from rabbit skeletal muscle by calmodulin and troponin
Author(s) -
Cohen Philip,
Picton Colin,
Klee Claude B.
Publication year - 1979
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(79)81078-9
Subject(s) - citation , library science , medicine , computer science
Phosphorylase kinase is of central importance in the nervous and hormonal control of glycogenolysis in mammalian skeletal muscle, since its activity is dependent on Ca*’ and stimulated by a phosphoryla- tion reaction catalysed by cyclic AMP-dependent protein kinase [ I]. Phosphorylase kinase from mammalian skeletal muscle has mol. wt 1 280 000 and possesses the struc- ture (@y8)4 where the o- and P-subunits are the components phosphorylated by cyclic AMP-dependent protein kinase [I] and the s-subunit is identical to the calcium binding protein termed calmodulin [2,3]. Calmodulin, formerly termed the modulator protein or calcium-dependent regulator protein, was originally identified as a factor which stimulated the activity of the high Km cyclic nucleotide phosphodiesterase of brain tissue [4,5] but it has subsequently been impli- cated in the control of a variety of intracellular processes which are regulated by Ca*’ [6-l 11. Calmodulin binds 4 Ca*‘/mol [ 121 and the calcium binding properties of phosphorylase kinase [ 131 support the view that all the high affinity binding sites for calcium are located on the 6-subunit [3]. This in turn suggests that the 6 -subunit is the compo- nent which confers calcium sensitivity to phosphorylase