Ca<sup>2+</sup>—calmodulin dependent myosin light‐chain phosphorylating activity in insulin‐secreting tissues

Penn, Elizabeth J.; Brocklehurst, Keith; Sopwith, A. M.; Hales, C. N.; Hutton, John C.

doi:10.1016/0014-5793(82)80474-2

Cited by 31 publications

(18 citation statements)

References 34 publications

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“…Although phosphorylation of ␤-granule proteins was demonstrated previously and proposed to play a role in insulin secretion (50,51), the identity of relevant phosphoprotein substrates is largely unknown. Furthermore, the intrinsic Ca 2ϩ -dependent phosphorylation of ␤-granule proteins had not been examined.…”

Section: Discussionmentioning

confidence: 99%

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Donelan

Morfini

Julyan

et al. 2002

Journal of Biological Chemistry

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The specific biochemical steps required for glucoseregulated insulin exocytosis from ␤-cells are not well defined. ] i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of ␤-granules from the storage pool to replenish the readily releasable pool of ␤-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca 2؉ -dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and ␤-granule transport in ␤-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca 2؉ ] i .

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Section: Discussionmentioning

confidence: 99%

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Donelan

Morfini

Julyan

et al. 2002

Journal of Biological Chemistry

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“…The 18-residue synthetic peptide (M-MLC6-23) corresponding to residues [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] with serine at position 23 of the amino acid sequence of the chicken gizzard myosin light chain reported by Maita et al (11) was a relatively poor 7471 The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C.…”

Section: Resultsmentioning

confidence: 99%

“…The role of this enzyme is presently best understood in the control of smooth muscle contraction (2,3). Nevertheless, it may have important physiological functions in other cell types, including platelets (4), macrophages (5), and pancreatic islets (6).…”

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confidence: 99%

Role of basic residues in the phosphorylation of synthetic peptides by myosin light chain kinase.

Kemp¹,

Pearson²,

House³

1983

Proc. Natl. Acad. Sci. U.S.A.

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“…It has been suggested that myosin is involved in intracellular transport in drosophila embryos (35), and that Ca 2+ /CaMdependent phosphorylation of the MLC controls insulin release (36); evidence for the presence of MLC kinase and its participation in the secretory machinery has been obtained (17,37). We recently demonstrated that its phosphorylation by either MLC kinase or CaM kinase II may control the granule movement, with distinct Ca 2+ requirements via phosphorylating the MLC kinase site of the light chain (17).…”

mentioning

confidence: 97%

Acetylcholine activates intracellular movement of insulin granules in pancreatic beta-cells via inositol trisphosphate-dependent [correction of triphosphate-dependent] mobilization of intracellular Ca2+.

et al. 1998

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Intracellular movement of secretory granules is a proximal stage in the secretory cascade that ends in the release product from cells. We investigated mechanisms underlying the control of this movement by acetylcholine using an insulinoma cell line, MIN6, in which acetylcholine increases both insulin secretion and granule movement. The peak activation of movement was observed 3 min after an acetylcholine challenge. The effects were nullified by the muscarinic inhibitor atropine, phospholipase C (PLC) inhibitors (D 609 and compound 48/80), and pretreatment with the Ca2+ pump inhibitor, thapsigargin. Inhibitors of Ca2+-dependent phospholipase A2 (arachidonyl trifluoromethyl ketone and methyl arachidonyl fluorophosphate) also partially inhibited the movement caused by acetylcholine, but downregulation of protein kinase C by overnight incubation with the phorbol ester 12-o-tetradecanoylphorbol-13-acetate failed to exert any influence. Acetylcholine stimulation of granule movement was not reproduced by membrane depolarization with high K+. Phosphorylation of the endogenous myosin light chain in MIN6 cells was increased by addition of acetylcholine and decreased by the Ca2+ chelator BAPTA (1,2-bis[2-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid). The calmodulin inhibitor W-7 and the myosin light-chain kinase inhibitor ML-9 decreased the motile events in the beta-cells under both nonstimulated and acetylcholine-stimulated conditions. These findings led us to conclude that inositol trisphosphate [corrected] causes Ca2+ mobilization by muscarinic activation of PLC, leading to intracellular translocation of insulin granules to the ready-releasable pool in pancreatic beta-cells via Ca2+/calmodulin-dependent phosphorylation of myosin light chains.

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Ca²⁺—calmodulin dependent myosin light‐chain phosphorylating activity in insulin‐secreting tissues

Cited by 31 publications

References 34 publications

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Role of basic residues in the phosphorylation of synthetic peptides by myosin light chain kinase.

Acetylcholine activates intracellular movement of insulin granules in pancreatic beta-cells via inositol trisphosphate-dependent [correction of triphosphate-dependent] mobilization of intracellular Ca2+.

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Ca2+—calmodulin dependent myosin light‐chain phosphorylating activity in insulin‐secreting tissues

Cited by 31 publications

References 34 publications

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Ca2+-dependent Dephosphorylation of Kinesin Heavy Chain on β-Granules in Pancreatic β-Cells

Role of basic residues in the phosphorylation of synthetic peptides by myosin light chain kinase.

Acetylcholine activates intracellular movement of insulin granules in pancreatic beta-cells via inositol trisphosphate-dependent [correction of triphosphate-dependent] mobilization of intracellular Ca2+.

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Ca²⁺—calmodulin dependent myosin light‐chain phosphorylating activity in insulin‐secreting tissues