scholarly journals The multiplicity of combinations of myosin light chains and heavy chains in histochemically typed single fibres. Rabbit soleus muscle

1987 ◽  
Vol 243 (3) ◽  
pp. 687-693 ◽  
Author(s):  
R S Staron ◽  
D Pette
Keyword(s):  
Cross Sections ◽  
Slow Light ◽  
Troponin I ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Adult Rabbit ◽  
Type I ◽  
Slow Myosin ◽  
Heavy Chains ◽  
Freeze Dried

1. Six adult rabbit soleus muscles were analysed by isolating histochemically identified fibre pieces from freeze-dried serial cross-sections. 2. By the use of this method, four fibre types (I, IC, IIC and IIA) were identified and analysed micro-electrophoretically. 3. Type I fibres contained the slow myosin heavy chain HCI and the slow myosin light chains LC1s and LC2s. 4. Type IIA fibres contained the fast myosin HCIIa with the fast light chains and, in addition, either LC1s or both LC1s and LC2s. 5. The C fibres (IC and IIC) represented intermediate populations between types I and IIC (IC) and between IC and IIA (IIC). They contained varied ratios of HCI/HCIIa with both sets of fast and slow light chains. With regard to myosin composition and isoforms of other myofibrillar proteins (M- and C-proteins, alpha-tropomyosin, troponin I), IC fibres resembled type I and IIC fibres resembled type IIA. 6. The presence of various myosin light and heavy chains within a specific fibre suggests a multiplicity of isomyosins. Without consideration of LC1sa and LC1sb differences, at least 54 possible isomyosins can be derived: type I fibres contain one isomyosin, types IC and IIC 54 possible isomyosins, and type IIA up to 18.

scholarly journals The multiplicity of combinations of myosin light chains and heavy chains in histochemically typed single fibres. Rabbit tibialis anterior muscle

1987 ◽  
Vol 243 (3) ◽  
pp. 695-699 ◽  
Author(s):  
R S Staron ◽  
D Pette
Keyword(s):  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Single Fibre ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Type I ◽  
Slow Myosin ◽  
Heavy Chains ◽  
Fast Myosin ◽  
Fast Light

1. Combined histochemical and biochemical single-fibre analyses [Staron & Pette (1987) Biochem. J. 243, 687-693], were used to investigate the rabbit tibialis-anterior fibre population. 2. This muscle is composed of four histochemically defined fibre types (I, IIC, IIA and IIB). 3. Type I fibres contain slow myosin light chains LC1s and LC2 and the slow myosin heavy chain HCI, and types IIA and IIB contain the fast myosin light chains LC1f, LC2f and LC3f and the fast heavy chains HCIIa and HCIIb respectively. 4. A small fraction of fibres (IIAB), histochemically intermediate between types IIA and IIB, contain the fast light myosin chains but display a coexistence of HCIIa and HCIIb. 5. Similarly to the soleus muscle, C fibres in the tibialis anterior muscle contain both fast and slow myosin light chains and heavy chains. The IIC fibres show a predominance of the fast forms and the IC fibres (histochemically intermediate between types I and IIC) a predominance of the slow forms. 6. A total of 60 theoretical isomyosins can be derived from these findings on the distribution of fast and slow myosin light and heavy chains in the fibres of rabbit tibialis anterior muscle.

scholarly journals Expression of myosin light chains during fetal development of human skeletal muscle

1987 ◽  
Vol 243 (2) ◽  
pp. 425-430 ◽  
Author(s):  
F Pons ◽  
A Damadei ◽  
J J Leger
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Slow Light ◽  
Minor Component ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Fetal Life ◽  
Fetal Period ◽  
Adult Muscle ◽  
A Minor

The expression of myosin light chains (MLCs) during the development of human skeletal muscle was investigated by using two different two-dimensional electrophoretic techniques. In both electrophoretic systems the predominant light chain 1 (LC1) expressed during the whole fetal period was found to co-migrate with the adult fast LC1 (LC1F). The main LC2 expressed during the whole fetal period was found to be different from the main fast LC2 (LC2F) and slow LC2 (LC2S) usually present in adult muscle, but co-migrated with a minor component often present in adult muscle. This fetal LC2 was phosphorylatable, and the phosphorylated form co-migrated with the main component of LC2F expressed in the adult. The adult fast LC3 appeared as early as week 20 of gestation, whereas the adult slow light chains (LC1S and LC2S) appeared only during the late fetal period. A minor component of LC1, previously described in humans as an ‘embryonic LC’ (LCemb.) [Strohman, Micou-Eastwood, Glass & Matsuda (1983) Science 221, 955-957], was only expressed in the early fetal period and was found to co-migrate with atrial LC1 (ALC1). We discuss the expression of these specific developmental forms of MLCs co-existing with immature myosin heavy chains during fetal life.

scholarly journals Changes in skeletal-muscle myosin isoenzymes with hypertrophy and exercise

1986 ◽  
Vol 238 (1) ◽  
pp. 55-63 ◽  
Author(s):  
P Gregory ◽  
R B Low ◽  
W S Stirewalt
Keyword(s):  
Slow Light ◽  
Peptide Mapping ◽  
Polyacrylamide Gel Electrophoresis ◽  
Fold Increase ◽  
Intermediate Stage ◽  
Skeletal Muscle Myosin ◽  
Slow Myosin ◽  
Heavy Chains ◽  
Myosin Isoenzymes ◽  
Slow Twitch

The patterns of myosin isoenzymes in fast- and slow-twitch muscles of the rat hindlimb were studied, by pyrophosphate/polyacrylamide-gel electrophoresis, with hypertrophy (induced by synergist removal) and with spontaneous running exercise of 4 and 11 weeks duration. At 11 weeks, changes with hypertrophy in the slow-twitch soleus, composed of greater than 95% SM2 (slow myosin 2) in normal muscles, were minor, and consisted of an increase in the SM1 and SM1′, and a loss of intermediate myosin (IM), an isoenzyme characteristic of Type IIa fibres [Fitzsimons & Hoh (1983) J. Physiol. (London) 343, 539-550]. The changes were dramatic, however, in the fast-twitch plantaris muscle. There was a 3-fold increase in the proportion of SM. In addition, IM became the predominant isoenzyme in the profile of hypertrophied plantaris by 4 weeks. These increases were balanced by decreases in the proportion of FM2 (fast myosin 2), with FM1 completely absent from the profile at 11 weeks. The changes in the plantaris with exercise were similar in direction but not as extensive as those with hypertrophy, and FM1 remained present at control levels throughout the study. When hypertrophy and exercise were combined, the increase in slow myosin was equal to the sum of the increases with each treatment alone. Changes at 4 weeks were intermediate between those of control and 11-week muscles. Peptide mapping of individual myosin isoenzymes showed that the heavy chains of IM were different from either fast or slow heavy chains. Furthermore, IM was found to be composed of a mixture of fast and slow light chains. These changes suggest that a transformation of myosin from fast to slow isoforms was in progress in the plantaris in response to hypertrophy, via a Type-IIa-myosin (IM) intermediate stage, a phenomenon similar to that occurring in chronically stimulated fast muscles during fast-to-slow transformation [Brown, Salmons & Whalen (1983) J. Biol. Chem. 258, 14686-14692].

scholarly journals Visualization of myosin in living cells.

1987 ◽  
Vol 105 (4) ◽  
pp. 1753-1760 ◽  
Author(s):  
B Mittal ◽  
J M Sanger ◽  
J W Sanger
Keyword(s):  
Living Cells ◽  
Stress Fibers ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Fluorescent Light ◽  
Heavy Chains ◽  
Free Region ◽  
The Reformation ◽  
Nonmuscle Cells ◽  
Dividing Cells

Myosin light chains labeled with rhodamine are incorporated into myosin-containing structures when microinjected into live muscle and nonmuscle cells. A mixture of myosin light chains was prepared from chicken skeletal muscle, labeled with the fluorescent dye iodoacetamido rhodamine, and separated into individual labeled light chains, LC-1, LC-2, and LC-3. In isolated rabbit and insect myofibrils, the fluorescent light chains bound in a doublet pattern in the A bands with no binding in the cross-bridge-free region in the center of the A bands. When injected into living embryonic chick myotubes and cardiac myocytes, the fluorescent light chains were also incorporated along the complete length of the A band with the exception of the pseudo-H zone. In young myotubes (3-4 d old), myosin was localized in aperiodic as well as periodic fibers. The doublet A band pattern first appeared in 5-d-old myotubes, which also exhibited the first signs of contractility. In 6-d and older myotubes, A bands became increasingly more aligned, their edges sharper, and the separation between them (I bands) wider. In nonmuscle cells, the microinjected fluorescent light chains were incorporated in a striated pattern in stress fibers and were absent from foci and attachment plaques. When the stress fibers of live injected cells were disrupted with DMSO, fluorescently labeled myosin light chains were present in the cytoplasm but did not enter the nucleus. Removal of the DMSO led to the reformation of banded, fluorescent stress fibers within 45 min. In dividing cells, myosin light chains were concentrated in the cleavage furrow and became reincorporated in stress fibers after cytokinesis. Thus, injected nonmuscle cells can disassemble and reassemble contractile fibers using hybrid myosin molecules that contain muscle light chains and nonmuscle heavy chains. Our experiments demonstrate that fluorescently labeled myosin light chains from muscle can be readily incorporated into muscle and nonmuscle myosins and then used to follow the dynamics of myosin distribution in living cells.

scholarly journals Epitopes of streptococcal M proteins shared with cardiac myosin.

1985 ◽  
Vol 162 (2) ◽  
pp. 583-591 ◽  
Author(s):  
J B Dale ◽  
E H Beachey
Keyword(s):  
Acute Rheumatic Fever ◽  
M Protein ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Myosin Heavy Chains ◽  
Cardiac Myosin ◽  
Poststreptococcal Glomerulonephritis ◽  
Heavy Chains ◽  
M Proteins ◽  
Group A

We present evidence that M proteins from three different serotypes of group A streptococci share epitopes with cardiac myosin. Rabbit antisera evoked by a purified fragment of type 5 M protein crossreacted with myosin, but not alpha-tropomyosin, actin, or myosin light chains. In enzyme-linked immunosorbent assays, the myosin-crossreactive antibodies were totally inhibited by type 5 M protein and partially inhibited by types 6 and 19 M proteins. The affinity-purified myosin antibodies opsonized type 5 streptococci, indicating that they were directed against protective M protein epitopes on the surface of the organisms. Immunoblot analyses demonstrated the binding of the crossreactive antibodies to myosin heavy chains. Sera from patients with acute rheumatic fever showed significantly stronger reactions with myosin than did sera from their siblings, hospitalized controls, or patients with poststreptococcal glomerulonephritis.

scholarly journals Distribution and properties of myosin isozymes in developing avian and mammalian skeletal muscle fibers

1982 ◽  
Vol 92 (2) ◽  
pp. 471-484 ◽  
Author(s):  
GF Gauthier ◽  
S Lowey ◽  
PA Benfield ◽  
AW Hobbs
Keyword(s):  
Early Development ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Slow Light ◽  
Muscle Fibers ◽  
Light Chains ◽  
Fiber Types ◽  
Mammalian Skeletal Muscle ◽  
Slow Myosin

Isozymes of myosin have been localized with respect to individual fibers in differentiating skeletal muscles of the rat and chicken using immunocytochemistry. The myosin light chain pattern has been analyzed in the same muscles by two-dimensional PAGE. In the muscles of both species, the response to antibodies against fast and slow adult myosin is consistent with the speed of contraction of the muscle. During early development, when speed of contraction is slow in future fast and slow muscles, all the fibers react strongly with anti-slow as well as with anti-fast myosin. As adult contractile properties are acquired, the fibers react with antibodies specific for either fast or slow myosin, but few fibers react with both antibodies. The myosin light chain pattern slow shows a change with development: the initial light chains (LC) are principally of the fast type, LC1(f), and LC2(f), independent of whether the embryonic muscle is destined to become a fast or a slow muscle in the adult. The LC3(f), light chain does not appear in significant amounts until after birth, in agreement with earlier reports. The predominance of fast light chains during early stages of development is especially evident in the rat soleus and chicken ALD, both slow muscles, in which LC1(f), is gradually replaced by the slow light chain, LC1(s), as development proceeds. Other features of the light chain pattern include an "embryonic" light chain in fetal and neonatal muscles of the rat, as originally demonstrated by R.G. Whalen, G.S. Butler- Browne, and F. Gros. (1978. J. Mol. Biol. 126:415-431.); and the presence of approximately 10 percent slow light chains in embryonic pectoralis, a fast white muscle in the adult chicken. The response of differentiating muscle fibers to anti-slow myosin antibody cannot, however, be ascribed solely to the presence of slow light chains, since antibody specific for the slow heavy chain continues to react with all the fibers. We conclude that during early development, the myosin consists of a population of molecules in which the heavy chain can be associated with a fast, slow, or embryonic light chain. Biochemical analysis has shown that this embryonic heavy chain (or chains) is distinct from adult fast or slow myosin (R.G. Whalen, K. Schwartz, P. Bouveret, S.M. Sell, and F. Gros. 1979. Proc. Natl. Acad. Sci. U.S.A. 76:5197-5201. J.I. Rushbrook, and A. Stracher. 1979. Proc Natl. Acad. Sci. U.S.A. 76:4331-4334. P.A. Benfield, S. Lowey, and D.D. LeBlanc. 1981. Biophys. J. 33(2, Pt. 2):243a[Abstr.]). Embryonic myosin, therefore, constitutes a unique class of molecules, whose synthesis ceases before the muscle differentiates into an adult pattern of fiber types.

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