Activation of Skeletal Muscle Phosphorylase b Kinase by CA<sup>2+ *</sup>

Meyer, William L.; Fischer, Edmond H.; Krebs, Edwin G.

doi:10.1021/bi00896a004

Cited by 253 publications

(72 citation statements)

References 19 publications

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“…Ca'+-dependent thiol protease (calpain) has been described by Guroff [l] and Meyer et al [2], and subsequently found in various mammalian and avian tissues (reviews, see . This family of proteases appears to catalyze limited proteolysis of a limited number of proteins, such as those related to contractile and cytoskeletal machineries .…”

Section: Introductionmentioning

confidence: 99%

A calcium‐protease activator associated with brain microsomal‐insoluble elements

et al. 1986

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A factor which markedly activates Caz+-dependent thiol protease (calpain) is associated with Triton X-lOOinsoluble materials, presumably structural elements such as cytoskeletons, of bovine brain microsomal fraction. This factor is extracted with 0.6 M KCl, and purified partially by sucrose density gradient centrifugation and hydroxyapatite column chromatography. The factor appears to be a heat-stable protein with an approximate M, of 15 000. With casein as substrate this factor activates both calpain I and calpain II severalfold up to more than lo-fold without alteration of their affinity to Ca 2+. Calmodulin is unable to substitute for this factor. A similar factor is associated with human platelet insoluble materials. Calpain Calpain activator Protease

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Section: Introductionmentioning

confidence: 99%

A calcium‐protease activator associated with brain microsomal‐insoluble elements

et al. 1986

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“…Moreover, we demonstrate that PHKG1 contains a composite 3′ terminal exon that results in a truncated transcript lacking the known C-terminal CaM binding domains. Given the fact that the catalytic activity of γ in the PhK complex is absolutely dependent on Ca 2+ [23,24], our findings suggest a potential alternative, Ca 2+ -independent γ activity in the cell.…”

Section: Introductionmentioning

confidence: 92%

In Silico characterization of phosphorylase kinase: Evidence for an alternate intronic polyadenylation site in PHKG1

Winchester

Rouchka

Rowland

et al. 2007

Molecular Genetics and Metabolism

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Phosphorylase kinase (PhK), the key enzyme that regulates glycogenolysis, has traditionally been thought to be expressed predominantly in muscle and liver. In this study, we show by two different database searches (Expressed Sequence Tag and UniGene) that PhK gene expression occurs in at least 28 -36 different tissues, and that the genes encoding the α, β and γ subunits of PhK undergo extensive transcriptional processing. In particular, we have identified exon 6 of PHKG1 as a 3′ composite terminal exon due to the presence of a weak polyadenylation and cleavage site in intron 6. We have verified biochemically that transcriptional processing of PHKG1 does occur in vivo; mRNA corresponding to the alternate variant is expressed in skeletal muscle, brain, heart, and tongue. In silico translation of this mRNA yields a PhK γ subunit that contains the first 181 residues of the protein, followed by an additional 21 amino acids. The implication of this alternate processing is discussed within the context of γ catalysis and regulation.

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“…However, in vitro both forms of phosphorylase kinase, the phosphorylated and the non-phosphorylated one, require 2 -20 pM free Ca2 + for half-maximal activation [5,13,[16][17][18][19][20][21]. The question of whether phosphorylation of phosphorylase kinase enhances its Ca2+ sensitivity has not yet been settled; results pointing in both directions have been obtained [5, 211.…”

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Dual function of calmodulin (δ) in phosphorylase kinase

Hessová

Varsányi

Heilmeyer

1985

European Journal of Biochemistry

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The Ca2 +-independent activity of fast skeletal muscle phosphorylase kinase, A,, can be reversibly stimulated by heparin more than 20-fold; concomitantly the Ca2+-dependent A2 activity is abolished completely. Heparin also drastically changes the aggregation state of the enzyme; aggregated species contain significantly less 6 and show an about fivefold higher A. activity than the tetrameric form containing 6 stoichiometrically. We interpret this to mean that 6 has two functions in the phosphorylase kinase: an inhibitory one with respect to A. and an activating one with respect to Az. The inhibition of A, by Ca2+-free 6 is released, i.e. A, increases when this subunit dissociates from the holoenzyme.is enriched from a crude extract to the same degree and approximately with the same yield as the major activity, A2. The phosphorylase kinase is not eluted from DEAEcellulose as a symmetrical bell-shaped protein peak. The peak fraction contains the activities A2 and AO,hep superimposed and yields a nearly homogeneous sedimentation boundary with an s20,w value of 25.5 S. The A, yields a much broader eluation profile showing a distinct maximum from the A2 activity which contains slower sedimenting species of 12

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Activation of Skeletal Muscle Phosphorylase b Kinase by CA^{2+ *}

Cited by 253 publications

References 19 publications

A calcium‐protease activator associated with brain microsomal‐insoluble elements

A calcium‐protease activator associated with brain microsomal‐insoluble elements

In Silico characterization of phosphorylase kinase: Evidence for an alternate intronic polyadenylation site in PHKG1

Dual function of calmodulin (δ) in phosphorylase kinase

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Activation of Skeletal Muscle Phosphorylase b Kinase by CA2+ *

Cited by 253 publications

References 19 publications

A calcium‐protease activator associated with brain microsomal‐insoluble elements

A calcium‐protease activator associated with brain microsomal‐insoluble elements

In Silico characterization of phosphorylase kinase: Evidence for an alternate intronic polyadenylation site in PHKG1

Dual function of calmodulin (δ) in phosphorylase kinase

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Product

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Activation of Skeletal Muscle Phosphorylase b Kinase by CA^{2+ *}