Calcium and calmodulin activation of muscle phosphorylase kinase

DePaoli‐Roach, Anna A.; Gibbs, Jackson B.; Roach, Peter J.

doi:10.1016/0014-5793(79)80639-0

Cited by 58 publications

(26 citation statements)

References 10 publications

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“…It was therefore of interest to examine the relative rates of dephosphorylation of sites l a , l b and 2 by this phosphatase. The relative rates of dephosphorylation were found to be: site 2 (100) > site l a (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) > site Ib) (< 1). The relative activity of the MgATP-dependent protein phosphatase against these sites was therefore very similar to protein phosphatase 1.…”

Section: Dephosphorylation Of Glycogen Synthase By the Mgatp-dependenmentioning

confidence: 99%

A Reinvestigation of the Phosphorylation of Rabbit Skeletal‐Muscle Glycogen Synthase by Cyclic‐AMP‐Dependent Protein Kinase

Embi

Parker

Cohen

1981

European Journal of Biochemistry

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Glycogen synthase preparations which were free of endogenous phosphorylase kinase were phosphorylated to different extents with cyclic-AMP-dependent protein kinase and the phosphopeptides obtained by tryptic digestion were analysed. Limited tryptic digestion of the native enzyme quantitatively released two phosphopeptides (site 1 a and site 1 b) which were soluble in trichloroacetic acid, The trichloroacetic-acid pellet contained a distinct phosphorylation site, which was shown to be identical to the serine residue which is phosphorylated by phosphorylase kinase (site 2).Sites l a , 1 b and 2 accounted for virtually all of the phosphorylation of glycogen synthase up to 2.5 molecules phosphate incorporated per subunit. Site 1 a was initially phosphorylated 7-10-fold faster than site 2, and 15-20-fold faster than site l b . The phosphorylation of site l a became much slower after about 0.5 molecules of phosphate had been incorporated per subunit.Cyclic-GMP-dependent protein kinase also phosphorylated glycogen synthase at sites 1 a, 1 b and 2. The order of phosphorylation was the same as that observed with cyclic-AMP-dependent protein kinase (site 1 a > site 2 > site 1 b).All three sites phosphorylated by cyclic-AMP-dependent protein kinase could be dephosphorylated by protein phosphatase 1. Site 2 was initially dephosphorylated 5 -10-fold faster than site 1 a and more than 100-fold faster than site 1 b. The MgATP-dependent protein phosphatase dephosphorylated site 2, site 1 a and site 1 b in a very similar manner to protein phosphatase 1.The different rates of phosphorylation and dephosphorylation of the three sites allowed the demonstration to be made that the activity of glycogen synthase depended on the state of phosphorylation of site 2 and site 1 a. The phosphorylation of site 1 b did not influence the activity under the conditions used.Incubation of glycogen synthase with high levels of phosphorylase kinase did not lead to the phosphorylation of either site 1 a or 1 b, or of the three sites phosphorylated by glycogen synthase kinase 3 (sites 3a, 3b and 3c). Similarly no phosphorylation of sites 3a, 3b or 3c by cyclic-AMP-dependent protein kinase was detected. It is concluded that site 2 is the only site at which overlapping substrate specificity occurs between these three glycogen synthase kinases.Glycogen synthase can exist as a dephosphorylated form of high activity, or as less active phosphorylated forms which require glucose 6-phosphate for activity [l, 21. Over the past few years several protein kinases have been identified which can decrease the activity of glycogen synthase in vitro [3 -191; which of these enzymes are important in regulating the activity of glycogen synthase in vivo has not yet been established.The first glycogen synthase kinase to be identified was cyclic-AMP-dependent protein kinase [20,21]. At first it was reported that this enzyme phosphorylated glycogen synthase to the extent of about 1 molecule per subunit, and that the activity ratio of the enzyme (defined as the activity in...

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Section: Dephosphorylation Of Glycogen Synthase By the Mgatp-dependenmentioning

confidence: 99%

A Reinvestigation of the Phosphorylation of Rabbit Skeletal‐Muscle Glycogen Synthase by Cyclic‐AMP‐Dependent Protein Kinase

Embi

Parker

Cohen

1981

European Journal of Biochemistry

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“…subunits to be degraded to lower M , species, but the y and 6 subunits are unaffected [3,26]. This limited proteolysis activates phosphorylase kinase to a level where it can no longer be further stimulated by the 6'-subunit [9,27]. It has been reported that the trypsinized enzyme no longer binds to calmodulin-Sepharose [27] indicating that the ability to interact with the 6'-subunit has been destroyed.…”

Section: Ejyect Of' Limited Proteolysis On the Interaction Qf The 6'-mentioning

confidence: 99%

“…This limited proteolysis activates phosphorylase kinase to a level where it can no longer be further stimulated by the 6'-subunit [9,27]. It has been reported that the trypsinized enzyme no longer binds to calmodulin-Sepharose [27] indicating that the ability to interact with the 6'-subunit has been destroyed. These results were confirmed in the present study (Table 2).…”

Section: Ejyect Of' Limited Proteolysis On the Interaction Qf The 6'-mentioning

confidence: 99%

Phosphorylase Kinase from Rabbit Skeletal Muscle Identification of the Calmodulin‐Binding Subunits

Picton

Klee

Cohen

1980

European Journal of Biochemistry

116

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Phosphorylase kinase has the structure (ct/?y8)4 where the &subunit is identical to the calciumbinding protein termed calmodulin [Shenolikar et al. (1979) Euu. J . Biochem. 100, 329-3371.The &subunit was tightly bound to phosphorylase kinase in the absence of calcium ions, and its rate of exchange with ['4C]calmodulin was only 15 %, per week. The &subunit remained associated with phophorylase kinase in the presence of 8 M urea provided that calcium ions were present and this property enabled electrophoretic techniques to be used which demonstrated that the b-subunit was associated with the y-subunit. This finding was confirmed by cross-linking experiments with dimethylsuberimidate which resulted in the formation of a y 6 complex.Phosphorylase kinase was shown to bind one additional molecule of calmodulin per .fly6 unit, termed the 6'-subunit. Glycerol gradient centrifugation in the presence of ['4C]calmodulin indicated that the interaction of the h'-subunit with phosphorylase kinase only occurred in the presence of calcium ions, and that the K d value was near 0.01 pM. This was similar to the concentration of 6 '-subunit which produced half-maximal activation. The 6'-subunit did not remain associated with phosphorylase kinase in the presence of 8 M urea, either in the presence or absence of calcium ions. The very slow exchange between the b-subunit and ['4C]calmodulin, and the calcium-dependent binding of the 6 '-subunit allowed cross-linking experiments to be used which demonstrated that the 6'-subunit was bound to both the a and p subunits. This result was supported by the finding that selective proteolysis of either the a-subunit, or the a and p subunits, decreased or abolished the ability of phosphorylase kinase to bind to calmodulin-Sepharose.The roles of the different subunits in the regulation of phosphorylase kinase activity are discussed.Phosphorylase kinase is the point at which the neural and hormonal mechanisms for stimulating glycogenolysis meet in a single enzyme, since its activity is dependent on Ca2+ and activated by phosphorylation catalysed by cyclic-AMP-dependent protein kinase (see [I] for a review).Phosphorylase kinase isolated from rabbit skeletal muscle has the subunit structure (ctpy6)4, where the molecular weights of the !

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“…In addition to the stimulatory effect of Ca 2ϩ mediated by the endogenous CaM (␦ subunit), which is essentially bound irreversibly to PbK, Ca 2ϩ is also required for the reversible binding of exogenous CaM to a different site on the holoenzyme (17)(18)(19). This exogenous CaM is termed ␦Ј, and it binds in a stoichiometry of one ␦Ј molecule/each ␣␤␥␦ protomer (12,20).…”

mentioning

confidence: 99%

The Structural Effects of Endogenous and Exogenous Ca2+/Calmodulin on Phosphorylase Kinase

Nadeau

Sacks

Carlson

1997

Journal of Biological Chemistry

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Calcium and calmodulin activation of muscle phosphorylase kinase

Cited by 58 publications

References 10 publications

A Reinvestigation of the Phosphorylation of Rabbit Skeletal‐Muscle Glycogen Synthase by Cyclic‐AMP‐Dependent Protein Kinase

A Reinvestigation of the Phosphorylation of Rabbit Skeletal‐Muscle Glycogen Synthase by Cyclic‐AMP‐Dependent Protein Kinase

Phosphorylase Kinase from Rabbit Skeletal Muscle Identification of the Calmodulin‐Binding Subunits

The Structural Effects of Endogenous and Exogenous Ca2+/Calmodulin on Phosphorylase Kinase

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