The skeletal muscle-specific glycogen-targeted protein phosphatase 1 plays a major role in the regulation of glycogen metabolism by adrenaline in vivo

2007 ◽  
Vol 19 (5) ◽  
pp. 1044-1055 ◽  
Author(s):  
Barry J. Toole ◽  
Patricia T.W. Cohen
Keyword(s):  
Skeletal Muscle ◽  
Protein Phosphatase ◽  
Glycogen Metabolism ◽  
Protein Phosphatase 1

scholarly journals Disruption of the striated muscle glycogen-targeting subunit of protein phosphatase 1: influence of the genetic background

2007 ◽  
Vol 40 (2) ◽  
pp. 47-59 ◽  
Author(s):  
James Paterson ◽  
Ian R Kelsall ◽  
Patricia T W Cohen
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Muscle Glycogen ◽  
Protein Phosphatase ◽  
Striated Muscle ◽  
Protein Phosphatase 1 ◽  
Phosphorylase Kinase ◽  
Donor Strain ◽  
Key Factor

A prediabetic phenotype of glucose intolerance, insulin resistance and obesity was observed at ∼12 months of age in mice homozygous for a null allele of the major skeletal muscle glycogen-targeting subunit GM of protein phosphatase 1 (PP1) and derived from a 129/Ola donor strain. In this study, backcrossing of these mice (termed obese mice) onto two different genetic backgrounds gave rise to lean, glucose-tolerant, insulin-sensitive mice (termed lean mice), indicating that at least one variant gene in the 129/Ola background, not present in the C57BL/6 or 129s2/sV background, is required for the development of the prediabetic phenotype of obese mice. Slightly elevated AMP-activated protein kinase α2 activity in the skeletal muscle of lean C57BL/6 mice was also observed to a lesser extent in the obese mice. Normal or slightly raised in vivo glucose transport in lean C57BL/6 mice compared with decreased glucose transport in the obese mice supports the tenet that adequate transport of glucose may be a key factor in preventing the development of the prediabetic phenotype. The pH 6.8/pH 8.6 activity ratio of phosphorylase kinase was increased in lean C57BL/6 mice compared with controls indicating that phosphorylase kinase is an in vivo substrate of PP1-GM.

scholarly journals Mutations of the serine phosphorylated in the protein phosphatase-1-binding motif in the skeletal muscle glycogen-targeting subunit

2000 ◽  
Vol 346 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Jun LIU ◽  
Jun WU ◽  
Carey OLIVER ◽  
Shirish SHENOLIKAR ◽  
David L. BRAUTIGAN
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Protein Phosphatase ◽  
Glycogen Metabolism ◽  
Binding Activity ◽  
Hormonal Control ◽  
Protein Phosphatase 1 ◽  
Binding Motif ◽  
Unique Contribution ◽  
Skeletal Muscle Glycogen

Cellular functions of protein phosphatase-1 (PP1) are determined by regulatory subunits that contain the consensus PP1-binding motif, RVXF. This motif was first identified as the site of phosphorylation by cAMP-dependent protein kinase (PKA) in a skeletal muscle glycogen-targeting subunit (GM). We reported previously that a recombinant fusion protein of glutathione S-transferase (GST) and the N-terminal domain of GM [GST-GM-(1-240)] bound PP1 in a pull down assay, and phosphorylation by PKA prevented PP1 binding. Here we report that substitution of either Ala or Val for Ser-67 in the RVS67F motif in GST-GM-(1-240) essentially eliminated PP1 binding. This was unexpected because other glycogen-targeting subunits have a Val residue at the position corresponding to Ser-67. In contrast, a mutation of Ser-67 to Thr (S67T) in GST-GM(1-240) gave a protein that bound PP1 the same as wild type and was unaffected by PKA phosphorylation. Full length GM tagged with the epitope sequence DYKDDDDK (FLAG) expressed in COS7 cells bound PP1 that was recovered by co-immunoprecipitation, but this association was prevented by treatment of the cells with forskolin. By comparison, PP1 binding with FLAG-GM(S67T) was not disrupted by forskolin treatment. Neither FLAG-GM(S67A) nor FLAG-GM(S67V) formed stable complexes with PP1 in COS7 cells. These results emphasise the unique contribution of Ser-67 in PP1 binding to GM. The constitutive PP1-binding activity shown by GM(S67T) opens the way for studying the role of GM multisite phosphorylation in hormonal control of glycogen metabolism.

Protein phosphorylation and the control of glycogen metabolism in skeletal muscle

1983 ◽  
Vol 302 (1108) ◽  
pp. 13-25 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Amp ◽  
Protein Phosphatase ◽  
Glycogen Synthase ◽  
Glycogen Metabolism ◽  
Catalytic Subunit ◽  
Glycogen Synthase Kinase ◽  
Dependent Protein Kinase ◽  
Dependent Protein

Glycogen metabolism in mammalian skeletal muscle is controlled by a regulatory network in which six protein kinases, four protein phosphatases and several thermostable regulatory proteins determine the activation state of glycogen phosphorylase and glycogen synthase, the rate-limiting enzymes of this process. Thirteen phosphorylation sites are involved, twelve of which have been isolated and sequenced and shown to be phosphorylated in vivo . The effects of adrenalin and insulin on the state of phosphorylation of each site have been determined. The neural control of glycogen metabolism is mediated by calcium ions and involves phosphorylase kinase, and a specific calmodulin-dependent glycogen synthase kinase. The β-adrenergic control of the system is mediated by cyclic AMP, and involves the phosphorylation of phosphorylase kinase, glycogen synthase and inhibitor 1 by cyclic-AMP-dependent protein kinase. Inhibitor 1 is a specific inhibitor of protein phosphatase 1, the major phosphatase involved in the control of glycogen metabolism. The stimulation of glycogen synthesis by insulin results from the dephosphorylation of glycogen synthase at sites (3 a + 3 b + 3 c ), which are introduced by the enzyme glycogen synthase kinase 3. The structure, regulation and substrate specificities of the protein phosphatases involved in glycogen metabolism are reviewed. Protein phosphatase 1 can exist in an inactive form termed the Mg-ATP-dependent protein phosphatase, which consists of a complex between the catalytic subunit and a thermostable protein termed inhibitor 2. Activation of this complex is catalysed by glycogen synthase kinase 3. It involves the phosphorylation of inhibitor 2 and its dissociation from the catalytic subunit. Protein phosphatase 2A can be resolved into three forms by ion exchange chromatography. These species contain the same catalytic subunit and other subunits that may have a regulatory function. Protein phosphatase 2B is a Ca 2+ -dependent enzyme composed of two subunits, A and B. Its activity is increased tenfold by calmodulin, which interacts with the A-subunit. The B-subunit is a Ca 2+ -binding protein that is homologous with calmodulin. Its N-terminus contains the unusual myristyl blocking group, only found previously in the catalytic subunit of cyclic-AMP-dependent protein kinase. Protein phosphatase 2C is a Mg 2+ -dependent enzyme that accounts for a very small proportion of the glycogen synthase phosphatase activity in skeletal muscle. It is likely to be involved in the regulation of other metabolic processes in vivo such as cholesterol synthesis. Recent evidence suggests that many of the proteins involved in the control of glycogen metabolism have much wider roles, and that they participate in the neural and hormonal regulation of a variety of intracellular processes.

The microtubule- and PP1-binding activities of Drosophila melanogaster Spc105 control the kinetics of SAC satisfaction.

2021 ◽  
Author(s):  
Margaux R. Audett ◽  
Erin L. Johnson ◽  
Jessica M. McGory ◽  
Dylan M. Barcelos ◽  
Evelin Oroszne Szalai ◽  
...  
Keyword(s):  
Protein Binding ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Protein Phosphatase 1 ◽  
Intrinsically Disordered ◽  
Regulatory Circuit ◽  
Cell Assays ◽  
Kinetics Of

KNL1 is a large intrinsically disordered kinetochore (KT) protein that recruits spindle assembly checkpoint (SAC) components to mediate SAC signaling. The N-terminal region (NTR) of KNL1 possesses two activities that have been implicated in SAC silencing: microtubule (MT) binding and protein phosphatase 1 (PP1) recruitment. The NTR of D. melanogaster KNL1 (Spc105) has never been shown to bind MTs nor to recruit PP1. Furthermore, the phospho-regulatory mechanisms known to control SAC protein binding to KNL1 orthologues is absent in D. melanogaster. Here, these apparent discrepancies are resolved using in vitro and cell based-assays. A phospho-regulatory circuit, which utilizes Aurora B kinase (ABK), promotes SAC protein binding to the central disordered region of Spc105 while the NTR binds directly to MTs in vitro and recruits PP1-87B to KTs in vivo. Live-cell assays employing an optogenetic oligomerization tag, and deletion/chimera mutants are used to define the interplay of MT- and PP1-binding by Spc105 and the relative contributions of both activities to the kinetics of SAC satisfaction. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

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