Troponin Subunits and Their Interactions

Greaser, M L; Yamaguchi, Masaru; Brekke, C. J.; Potter, James D.; Gergely, J.

doi:10.1101/sqb.1973.037.01.033

Cited by 88 publications

(38 citation statements)

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“…The electrophoresis of tropomyosin showed two bands of molecular weights 37000 and 35000 and that of' troponin contained three major polypeptides with molecular weights of 37 000, 23 000 and 20000. These molecular weights correspond to previously described values [18].…”

Section: Purity Of the Proteinssupporting

confidence: 87%

Interaction of Contractile Proteins with DNA

Corcés¹,

Ávila²

1978

Eur J Biochem

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The interaction of contractile proteins (myosin, actin, tropomyosin and troponin) with DNA was studied in vitro using a nitrocellulose filter binding technique. The data indicate a high affinity of myosin and troponin for DNA, a lesser interaction between DNA and tropomyosin and the absence of binding of actin to DNA. When binding to DNA was detected, the interaction was higher with single-stranded DNA than with RNA or double-stranded DNA, although in some conditions myosin binds equally as well to native as to denatured eukaryotic DNA.Myosin binds better to eukaryotic than to phage native DNA.The characterization of non-histone chromatin proteins and their possible correlation with proteins of known biological functions is a current problem. There is some evidence that contractile proteins, such as myosin, actin, and others [I -41, exist among the nonhistone chromatin proteins. These proteins are present not only in the muscle but in other tissues; for example, myosin, tropomyosin, actin and a troponin C subunit-like protein have been found in the cytoplasmic and nuclear fractions from fibroblasts [5 -81. Other authors have also reported the existence of myosin and actin in the mitotic spindle [9,10], and recently Cande et al. [ l l ] have shown the existence of actin in the fibers running from the kinetochore of the chromosome to the pole in the mitotic spindle. This evidence suggests the possibility of the interaction of contractile proteins with the chromosome. This interaction could occur during the whole cell cycle or, perhaps, in one phase only.If a protein is associated to chromatin it must have affinity for DNA, another chromosomal protein or other chromosomal components. Therefore, the affinity for purified DNA can give some insight on the possible interaction of a protein with chromatin. In this report we show some DNA-binding properties of contractile proteins (myosin, actin, tropomyosin and troponin) isolated from muscle microfilaments. Our results indicate that troponin and myosin have a high affinity for DNA, tropomyosin has a weaker interaction with DNA and actin does not bind to DNA. Abhrericrzion. EGTA, [ethylenebis(oxyethylenenitrilo)]tetraace-Enzjwes. Myosin ATPase (EC 3.6.1.3); nuclease Sl (EC tic acid. 3.1.4.21).Moreover, we show that myosin binds better to eukaryotic than to phage DNA. MATERIALS AND METHODS Protein PreparationsMyosin was purified from pig leg muscle following the procedure of Richards et al. [12]. Ground muscle was extracted with a solution containing 0.67 M KC1, 5 mM KH,PO,/Na,HPO,, 5 mM MgCl, and 10 mM sodium pyrophosphate. Myosin was precipitated by adding 9 vol. of water, resuspended in 0.3 M KC1 and dialyzed against 0.15 M potassium phosphate, pH 7.5 (25 "C). 40 mg of protein were chromatographed on a 15-ml DEAE-Sephadex column as described by Godfrey and Harrington [13]. The eluted myosin was dialyzed against 0.15 M potassium phosphate, pH 7.5, 10 mM EDTA, and 50% glycerol and stored at -20 "C. The usual specific activity of the myosin ATPase was approximately 50 nm...

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Section: Purity Of the Proteinssupporting

confidence: 87%

Interaction of Contractile Proteins with DNA

Corcés¹,

Ávila²

1978

Eur J Biochem

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“…sTnC was prepared from rabbit skeletal muscle according to the method of [22]. cTnC was prepared from bovine heart according to a method by Stepkowski and Drabikowski (unpublished results).…”

Section: Methodsmentioning

confidence: 99%

Calcium and Cadmium Binding to Troponin C

Teleman¹,

Drakenberg²,

Forsén³

et al. 1983

European Journal of Biochemistry

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Proton NMR is used to compare the structural changes induced in bovine cardiac troponin C on binding of cadmium and calcium ions. The same spectral changes are observed for both ion species. The rate of the conformational changes associated with cadmium binding to the two high‐affinity sites is slow, that associated with cadmium ions binding to the low‐affinity site is high. 113Cd‐NMR spectra of cardiac troponin C feature two signals interpreted as due to cadmium ions bound to the strong sites. Strong arguments are given in favour of cooperativity in binding of the first two cadmium or calcium ions to cardiac and skeletal muscle troponin C.

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“…Rabbit troponin is a complex of three different proteins: troponin-C (Tn-C, 17,900 in molecular weight), which binds calcium, troporuin-I (Tn-I, 20,900), which inhibits actin-myosin interaction in the presence and absence of calcium, and troponin-T (Tn-T, 30,500), which binds to tropomyosin. All three components, present in a 1:1:1 molar ratio, are required for full calcium sensitization of the actomyosin ATPase (2)(3)(4). A full understanding at the molecular level of the ways in which these proteins interact with each other and with the actomyosin complex during contraction and relaxation will require a detailed knowledge of their threedimensional structures.…”

mentioning

confidence: 99%

Amino-acid sequence of tropomyosin-binding component of rabbit skeletal muscle troponin.

Pearlstone¹,

Carpenter²,

Johnson³

et al. 1976

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

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The complete amino-acid sequence of rabbit skeletal troponin-T is reported. The protein consists of a single polypeptide chain of 259 amino acids; it has an acetylated amino terminus and a molecular weight of 30,503. The sequence was determined by manual and/or automated Edman degradation techniques on the six fragments obtained after cleavage with cyanogen bromide. The larger fragments were further digested with trypsin, chymotrypsin, alpha-lytic protease, thermolysin, or pepsin to obtain smaller fragments suitable for manual sequencing. About 50% of the residues are charged at neutral pH with highly acidic amino-terminal (residues 1-39) and highly basic carboxyl-terminal regions (residues 221-259). Predictions of secondary structure indicate 37% helical content with two long sections (residues 80-102 and 122-146) in that portion of the molecule implicated in binding to tropomyocin. Two of the three phosphorylated sites in the molecule are located at serine-1 and serine-149 or -150. The sequence about the latter site resembles somewhat the phosphorylase kinase phosphorylation sites in phosphorylase alpha and troponin-I.

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Troponin Subunits and Their Interactions

Cited by 88 publications

References 0 publications

Interaction of Contractile Proteins with DNA

Interaction of Contractile Proteins with DNA

Calcium and Cadmium Binding to Troponin C

Amino-acid sequence of tropomyosin-binding component of rabbit skeletal muscle troponin.

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