scholarly journals Embryonic chicken skeletal, cardiac, and smooth muscles express a common embryo-specific myosin light chain.

1985 ◽  
Vol 100 (6) ◽  
pp. 2025-2030 ◽  
Author(s):  
H Takano-Ohmuro ◽  
T Obinata ◽  
M Kawashima ◽  
T Masaki ◽  
T Tanaka
Keyword(s):  
Light Chain ◽  
Gel Electrophoresis ◽  
Myosin Light Chain ◽  
Smooth Muscles ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Striated Muscles ◽  
Two Dimensional Gel Electrophoresis ◽  
Embryonic Chicken ◽  
Muscle Myosin

It has been demonstrated that embryonic chicken gizzard smooth muscle contains a unique embryonic myosin light chain of 23,000 mol wt, called L23 (Katoh, N., and S. Kubo, 1978, Biochem. Biophys. Acta, 535:401-411; Takano-Ohmuro, H., T. Obinata, T. Mikawa, and T. Masaki, 1983, J. Biochem. (Tokyo), 93:903-908). When we examined myosins in developing chicken ventricular and pectoralis muscles by two-dimensional gel electrophoresis, the myosin light chain (Le) that completely comigrates with L23 was detected in both striated muscles at early developmental stages. Two monoclonal antibodies, MT-53f and MT-185d, were applied to characterize the embryonic light chain Le of striated muscles. Both monoclonal antibodies were raised to fast skeletal muscle myosin light chains; the former antibody is specific to fast muscle myosin light chains 1 and 3, whereas the latter recognizes not only fast muscle myosin light chains but also the embryonic smooth muscle light chain L23. The immunoblots combined with both one- and two-dimensional gel electrophoresis showed that Le reacts with MT-185d but not with MT-53f. These results strongly indicate that Le is identical to L23 and that embryonic chicken skeletal, cardiac, and smooth muscles express a common embryo-specific myosin light chain.

Smooth muscle phosphatases: structure, regulation, and function

1994 ◽  
Vol 72 (11) ◽  
pp. 1427-1433 ◽  
Author(s):  
M. D. Pato ◽  
A. G. Tulloch ◽  
M. P. Walsh ◽  
E. Kerc
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Protein Phosphatases ◽  
Smooth Muscles ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Heavy Meromyosin ◽  
Smooth Muscle Contractility

Smooth muscle contraction is regulated primarily by the reversible phosphorylation of myosin by myosin light chain kinase. Secondary mechanisms that might modulate contractility are phosphorylation–dephosphorylation of myosin light chain kinase and thin-filament proteins, caldesmon and calponin. Purification of several protein phosphatases that are active toward myosin light chains and (or) myosin and heavy meromyosin from smooth muscles has been reported. All the cytosolic turkey gizzard smooth muscle phosphatases, termed SMP-I, -II, -III, and -IV, dephosphorylate myosin light chains rapidly, but only SMP-III and -IV are active toward myosin and heavy meromyosin, suggesting that SMP-III and -IV might be directly involved in the relaxation of smooth muscle. SMP-III and -IV exhibit properties typical of type 1 protein phosphatases following tryptic digestion. These enzymes appear to share structural similarity with myofibrillar phosphatase PP1M. Purified calponin phosphatase and caldesmon phosphatase from chicken gizzards are structurally and immunologically identical with SMP-I, a type 2A protein phosphatase. SMP-I dephosphorylates calponin faster than it does caldesmon, and has much higher activity toward these substrates than SMP-II, -III, and -IV. Thus, one role for SMP-I might be to regulate the activities of caldesmon and calponin. Since SMP-I is active toward myosin light chain kinase, it might also modulate this enzyme.Key words: smooth muscle, contractility, protein phosphatases, smooth muscle phosphatases.

scholarly journals Resolution of Myocardial Myosin Light Chains by Two-Dimensional Gel Electrophoresis

1974 ◽  
Vol 249 (3) ◽  
pp. 994-996
Author(s):  
John McPherson ◽  
Robert R. Traut ◽  
Dean T. Mason ◽  
Robert Zelis ◽  
Joan Wikman-Coffelt
Keyword(s):  
Gel Electrophoresis ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis

scholarly journals Myosin light chain kinase-regulated endothelial cell contraction: the relationship between isometric tension, actin polymerization, and myosin phosphorylation.

1995 ◽  
Vol 130 (3) ◽  
pp. 613-627 ◽  
Author(s):  
Z M Goeckeler ◽  
R B Wysolmerski
Keyword(s):  
Endothelial Cell ◽  
Light Chain ◽  
Isometric Contraction ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Isometric Tension ◽  
Stress Fibers ◽  
Light Chains ◽  
Myosin Light Chains

The phosphorylation of regulatory myosin light chains by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK) has been shown to be essential and sufficient for initiation of endothelial cell retraction in saponin permeabilized monolayers (Wysolmerski, R. B. and D. Lagunoff. 1990. Proc. Natl. Acad. Sci. USA. 87:16-20). We now report the effects of thrombin stimulation on human umbilical vein endothelial cell (HUVE) actin, myosin II and the functional correlate of the activated actomyosin based contractile system, isometric tension development. Using a newly designed isometric tension apparatus, we recorded quantitative changes in isometric tension from paired monolayers. Thrombin stimulation results in a rapid sustained isometric contraction that increases 2- to 2.5-fold within 5 min and remains elevated for at least 60 min. The phosphorylatable myosin light chains from HUVE were found to exist as two isoforms, differing in their molecular weights and isoelectric points. Resting isometric tension is associated with a basal phosphorylation of 0.54 mol PO4/mol myosin light chain. After thrombin treatment, phosphorylation rapidly increases to 1.61 mol PO4/mol myosin light chain within 60 s and remains elevated for the duration of the experiment. Myosin light chain phosphorylation precedes the development of isometric tension and maximal phosphorylation is maintained during the sustained phase of isometric contraction. Tryptic phosphopeptide maps from both control and thrombin-stimulated cultures resolve both monophosphorylated Ser-19 and diphosphorylated Ser-19/Thr-18 peptides indicative of MLCK activation. Changes in the polymerization of actin and association of myosin II correlate temporally with the phosphorylation of myosin II and development of isometric tension. Activation results in a 57% increase in F-actin content within 90 s and 90% of the soluble myosin II associates with the reorganizing F-actin. Furthermore, the disposition of actin and myosin II undergoes striking reorganization. F-actin initially forms a fine network of filaments that fills the cytoplasm and then reorganizes into prominent stress fibers. Myosin II rapidly forms discrete aggregates associated with the actin network and by 2.5 min assumes a distinct periodic distribution along the stress fibers.

scholarly journals Two-dimensional gel electrophoretic analysis of the MT3 and DR4 molecules from the different D-typed cells.

1984 ◽  
Vol 160 (3) ◽  
pp. 751-758 ◽  
Author(s):  
M Suzuki ◽  
T Yabe ◽  
M Satake ◽  
T Juji ◽  
H Hamaguchi
Keyword(s):  
Light Chain ◽  
Gel Electrophoresis ◽  
Electrophoretic Analysis ◽  
Structural Heterogeneity ◽  
Class Ii ◽  
Light Chains ◽  
Two Dimensional ◽  
Structural Polymorphism ◽  
Two Dimensional Gel Electrophoresis

This report demonstrates directly, using two-dimensional gel electrophoresis and alloantisera, the following: (a) The DR4 light chains show a structural polymorphism among the Dw4, DKT2, and DYT cells. (b) Most of the class II light chains consist of the DR light chain. (c) The MT3 molecule is distinct from the DR4 molecule in the Dw4, DKT2, and DYT cells. (d) The MT3 molecule does not show any structural heterogeneity among the Dw4, DKT2, and DYT cells. These results suggest that the dissection of the D specificity among Dw4, DKT2, and DYT is mainly caused by the differences of the DR4 molecules.

Effect of muscle length on isometric stress and myosin light chain phosphorylation in gallbladder smooth muscle

1991 ◽  
Vol 260 (6) ◽  
pp. G920-G924 ◽  
Author(s):  
R. J. Washabau ◽  
M. B. Wang ◽  
C. L. Dorst ◽  
J. P. Ryan
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Muscle Length ◽  
Stress Sensitivity ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Myosin Light Chain Phosphorylation ◽  
Myofilament Activation

These experiments were designed to characterize the effect of muscle length on isometric stress, sensitivity to stimulation, and phosphorylation of the 20,000-Da myosin light chains in guinea pig gallbladder smooth muscle. Basal, active, and total isometric stress were determined in acetylcholine- or K(+)-treated (10(-4) M ACh, 80 mM KCl) muscle strips at 0.6-1.3 times the optimal muscle length (Lo) for isometric stress development. The effect of muscle length on the sensitivity to ACh and K+ was determined in cumulative dose-response experiments (10(-8) to 10(-4) M ACh, 10-80 mM KCl) at 0.7, 1.0, and 1.3 Lo. The effect of muscle length on myosin light chain phosphorylation was determined in ACh- or K(+)-treated (10(-4) M ACh, 80 mM KCl) muscle strips at 0.7, 1.0, and 1.3 Lo. In gallbladder smooth muscle, 1) active isometric stresses at 0.7 and 1.3 Lo were less than active isometric stress at 1.0 Lo; 2) the sensitivity of developed stress was similar at 1.0 and 1.3 Lo but decreased at 0.7 Lo; 3) the decline in isometric stress and sensitivity at 0.7 Lo was associated with reduced levels of phosphorylated myosin light chain; and 4) the decline in isometric stress at 1.3 Lo was not associated with reduced amounts of phosphorylated myosin light chain. These results suggest that the decline in active stress and sensitivity at short muscle lengths (L less than Lo) in gallbladder smooth muscle is due, at least in part, to decreases in the activation of the myofilaments. The decline in active isometric stress at long muscle lengths (L greater than Lo) is not due to changes in myofilament activation.

Myosin light chain phosphorylation and tension development in stretch-activated arterial smooth muscle.

1984 ◽  
Vol 30 (12) ◽  
pp. 2063-2068 ◽  
Author(s):  
R F Ledvora ◽  
M Bárány ◽  
K Bárány
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Carotid Arteries ◽  
Chelating Agent ◽  
Prolonged Treatment ◽  
Light Chains ◽  
Active Tension ◽  
Two Dimensional Gel Electrophoresis ◽  
Tension Development

Abstract Phosphorylation of the 20 000-Da light chain of myosin in functionally different porcine carotid arteries was determined, with use of two-dimensional gel electrophoresis. Stretching arteries to 1.7 times their resting length resulted in maximal phosphorylation. Intracellular Ca2+ was mobilized for stretch-induced light chain phosphorylation. Releasing the stretch from the arteries produced active tension spontaneously, without the participation of any exogenous stimulating agent. Prolonged treatment of arteries with a chelating agent (EGTA) not only abolished stretch-induced phosphorylation, it also prevented the development of active tension when the stretch was released. However, when the EGTA was washed out and the strips were restretched and again released, the stretch-induced phosphorylation and the stretch-release-induced active tension were restored. Evidently, arteries must contain phosphorylated light chain if they are to produce active tension. The myosin light chain became partly dephosphorylated in arteries that developed active tension when the stretch was released, but more than half of the light chains remained phosphorylated. This result suggests that phosphorylation of light chain is involved, not in the generation of active tension, but rather in activation of smooth muscle.

scholarly journals Fast myosin light chain expression in chicken muscles studied by in situ hybridization.

1992 ◽  
Vol 40 (10) ◽  
pp. 1547-1557 ◽  
Author(s):  
R Billeter ◽  
M Messerli ◽  
E Wey ◽  
A Puntschart ◽  
K Jostarndt ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Fiber Type ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Two Dimensional ◽  
Fast Myosin ◽  
Chicken Muscles

We have studied the fiber type-specific expression of the fast myosin light chain isoforms LC 1f, LC 2f, and LC 3f in adult chicken muscles using in situ hybridization and two-dimensional gel electrophoresis. Type II (fast) fibers contain all three fast myosin light chain mRNAs; Types I and III (slow) fibers lack them. The myosin light chain patterns of two-dimensional gels from microdissected single fibers match their mRNA signals in the in situ hybridizations. The results confirm and extend previous studies on the fiber type-specific distribution of myosin light chains in chicken muscles which used specific antibodies. The quantitative ratios between protein and mRNA content were not the same for all three fast myosin light chains, however. In bulk muscle samples, as well as in single fibers, there was proportionally less LC 3f accumulated for a given mRNA concentration than LC 1f or LC 2f. Moreover, the ratio between LC 3f mRNA and protein was different in samples from muscles, indicating that LC 3f is regulated somewhat differently than LC 1f and LC 2f. In contrast to other in situ hybridization studies on the fiber type-specific localization of muscle protein mRNAs, which reported the RNAs to be located preferentially at the periphery of the fibers, we found all three fast myosin light chain mRNAs quite evenly distributed within the fiber's cross-sections, and also in the few rare fibers which showed hybridization signals several-fold higher than their surrounding counterparts. This could indicate principal differences in the intracellular localization among the mRNAs coding for various myofibrillar protein families.

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