Phosphorylation of fibroblast myosin

Mühlrád, András; Oplatka, Avraham

doi:10.1016/0014-5793(77)80188-9

Cited by 30 publications

(8 citation statements)

References 13 publications

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“…Despite studies showing that MHC phosphorylation is the primary mechanism regulating filament assembly in the model organisms Dictyostelium discoideum and Acanthamoeba castelanii [24;50;76], as well as studies beginning in the late 1970's showing that mammalian MHCs could be phosphorylated [33;55], a deeper understanding of this regulatory mechanism in mammalian cells has been somewhat slow in coming. This is perhaps due in part to neglect following the discovery in the mid-1970's that the assembly of NM2 into filaments, as well as its actin-activated ATPase activity, were both dramatically activated by RLC phosphorylation [1;35].…”

Section: Isoform-specific Mhc Phosphorylationmentioning

confidence: 99%

Myosin II isoform co-assembly and differential regulation in mammalian systems

Beach

Hammer

2015

Experimental Cell Research

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Non-muscle myosin 2 (NM2) is a major force-producing, actin-based motor in mammalian non-muscle cells, where it plays important roles in a broad range of fundamental biological processes, including cytokinesis, cell migration, and epithelial barrier function.. This breadth of function at the tissue and cellular levels suggests extensive diversity and differential regulation of NM2 bipolar filaments, the major, if not sole, functional form of NM2s in vivo. Previous in vitro, cellular and animal studies indicate that some of this diversity is supported by the existence of multiple NM2 isoforms. Moreover, two recent studies have shown that these isoforms can co-assemble to form heterotypic filaments, further expanding functional diversity. In addition to isoform co-assembly, cells may differentially regulate NM2 function via isoform-specific expression, RLC phosphorylation, MHC phosphorylation or regulation via binding partners. Here, we provide a brief summary of NM2 filament assembly, summarize the recent findings regarding NM2 isoform co-assembly, consider the mechanisms cells might utilize to differentially regulate NM2 isoforms, and review the data available to support these mechanisms.

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Section: Isoform-specific Mhc Phosphorylationmentioning

confidence: 99%

Myosin II isoform co-assembly and differential regulation in mammalian systems

Beach

Hammer

2015

Experimental Cell Research

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“…Phosphorylation of the corresponding light chain was subsequently found to stimulate actin activation of smooth muscle myosin (138)(139)(140)(141) and, in this case, also to confer a requirement for Ca2+ to the actomyosin. Phosphorylation of the heavy chain, as well as the 20,000-dalton light chain, of fibroblast myosin was reported recently (142), but the effect of these phosphorylations on the myosin ATPase activity was not measured. Phosphorylation of fibroblast myosin heavy chain may be similar to the phosphorylation of spectrin (87)(88)(89).…”

Section: Biochemistry Of Nonmuscle Myosinsmentioning

confidence: 99%

“…Direct evidence for tropomyosin in mammalian nonmuscle cells was provided by its isolation from human and calf platelets, calf brain and pancreas, and mouse fibroblasts (141)(142)(143)(144)(145)(146)(147) The troponin complex from vertebrate skeletal muscle contains equimolar amounts of a 37,000-dalton troponin T (the tropomyosin-binding subunit), a 24,000-dalton troponin I (the inhibitory subunit), and an 18,000-daltqn troponin C (the Ca2+-binding subunit). The Ca2+ requirements of partially purified human platelet actomyosin (149) and rat brain actomyosin (150) have been attributed to mixtures of tropomyosin and three presumably troponin-like peptides with apparent molecular weights of 36,000, 18,000, and 14,000 (in platelets) and 38,000, 27,000, and 20,000 (in rat brain).…”

Section: Biochemistry Of Nonmuscle Myosinsmentioning

confidence: 99%

Biochemistry of actomyosin-dependent cell motility (a review).

Korn¹

1978

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

449

108

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Actins akd myosins similar to the major proteins of muscle are the major molecular components of intricate mechanochemical systems that perform numerous vital motility and structural functions in all eukaryotic cells. In this article, after a brief summary of the morphological distribution and ultrastructure of actin, myosin, and interrelated proteins of nonmuscle cells, our present knowledge of their biochemistry is critically appraised from the perspective that understanding complex cellular processes depends ultimately on the identification, purification, and biochemical characterization of the proteins involved. Although few conclusions are reached, possible molecular mechanisms for cellular regulation of actin polymerization, filament association, actomyosin ATPase activity, and mechanochemical coupling are discussed and a number of potentially fruitful directions for further research are suggested. These include comparative biochemical investigations and the study of the interaction of heterologous proteins, but particular emphasis is given to the need for quantitative studies at the molecular level of motility proteins purified from a single cellular source.Three mechanisms, ultrastructurally, biochemically, and mechanically distinct, have evolved for cell motility. Two of these, bacterial flagella (1, 2) and eukaryotic flagella (3-6), serve to move cells through fluid media, but they function differently. The third motile mechanism, that based on cytoplasmic microfilaments, is responsible for ameboid-type movement of a cell on a solid substratum. The major component of cytoplasmic microfilaments is the protein actin. Presumably, myosin (which is an ATPase that forms an enzymatically active complex with actin) provides the energy for the motility events, while a number of other proteins maintain the dynamic structural organization of the system and regulate its action. Similar systems in all eukaryotic cells (protist, plant, and animal, and including cells that also possess flagella) provide the mechanochemical basis for many other diverse cellular activities, including cytoplasmic streaming and saltatory movements, phagocytosis and secretory processes, cell division and possibly chromosome segregation, changes in cell shape, and probably even the regulation of the topographical distribution of membrane proteins and functional interconnections of the cell membrane with the nucleus (7-15). Some of these functions may have preceded in evolution the role of actin and myosin in ameboid movement. In their most recently evolved forms, actin and myosin comprise the highly structured contractile systems of muscles.Actomyosin-based cell motility and related phenomena such as the cytoskeletal role of microfilaments and the interaction of microfilaments with cell membranes are increasingly the subjects of investigation at the cellular level and in crude cell extracts. I believe, however, that to understand the physiology of cellular events it is first necessary to understand their biochemistry. It is necess...

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“…Cells from 40 plates of differentiated 3T3-L1 cells were pooled, and crude actomyosin was prepared from them by the method of Muhlrad & Oplatka (1977). The resulting actomyosin was phosphoryl-ated with endogenous kinase exactly as described by Muhlrad & Oplatka (1977), except that NaCl was substituted for KCI, and the specific radioactivity of the [y-32P]ATP used was about 1000c.p.m./pmol.…”

Section: Preparation and Phosphorylation Of Myosin Light Chainmentioning

confidence: 99%

Insulin and growth factors stimulate the phosphorylation of a Mr-22000 protein in 3T3-L1 adipocytes

Blackshear¹,

Nemenoff²,

Avruch³

1983

Biochemical Journal

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Insulin, epidermal growth factor (EGF), platelet-derived growth factor, multiplication-stimulating activity and 10% foetal-calf serum each stimulated the phosphorylation of a cytosolic Mr-22000 acidic heat-stable protein in Swiss mouse 3T3-L1 adipocytes. Phosphorylation of this protein was not stimulated by isoprenaline or dibutyryl cyclic AMP. The effect of insulin was maximal (3-fold increase) by 10 min; half-maximal stimulation was observed at 70 pM-insulin. Both [32P]phosphoserine and [32P]phosphothreonine residues were present in the Mr-22000 protein after insulin- and growth-factor-stimulated phosphorylation, but no [32P]phosphotyrosine. The major site of insulin- and EGF-stimulated phosphorylation appeared to be a threonine residue, in contrast with previously studied insulin-stimulated phosphorylation of serine residues. Insulin treatment appeared to result in a shift of the protein toward the anode on isoelectric focusing. Insulin and EGF present simultaneously did not lead to phosphorylation beyond that seen with each hormone singly. We surmise that insulin, EGF and perhaps other growth factors may activate a common protein kinase or inhibit a common protein phosphatase in 3T3-L1 adipocytes which acts on the Mr-22000 protein.

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Phosphorylation of fibroblast myosin

Cited by 30 publications

References 13 publications

Myosin II isoform co-assembly and differential regulation in mammalian systems

Myosin II isoform co-assembly and differential regulation in mammalian systems

Biochemistry of actomyosin-dependent cell motility (a review).

Insulin and growth factors stimulate the phosphorylation of a Mr-22000 protein in 3T3-L1 adipocytes

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