scholarly journals The major myosin-binding domain of skeletal muscle MyBP-C (C protein) resides in the COOH-terminal, immunoglobulin C2 motif.

1993 ◽  
Vol 123 (3) ◽  
pp. 619-626 ◽  
Author(s):  
T Okagaki ◽  
F E Weber ◽  
D A Fischman ◽  
K T Vaughan ◽  
T Mikawa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Variable Number ◽  
Terminal Sequence ◽  
C Protein ◽  
C2 Domains ◽  
Type Iii ◽  
Myosin Filaments ◽  
Fibronectin Type Iii ◽  
Myosin Binding

A common feature shared by myosin-binding proteins from a wide variety of species is the presence of a variable number of related internal motifs homologous to either the Ig C2 or the fibronectin (Fn) type III repeats. Despite interest in the potential function of these motifs, no group has clearly demonstrated a function for these sequences in muscle, either intra- or extracellularly. We have completed the nucleotide sequence of the fast type isoform of MyBP-C (C protein) from chicken skeletal muscle. The deduced amino acid sequence reveals seven Ig C2 sets and three Fn type III motifs in MyBP-C. alpha-chymotryptic digestion of purified MyBP-C gives rise to four peptides. NH2-terminal sequencing of these peptides allowed us to map the position of each along the primary structure of the protein. The 28-kD peptide contains the NH2-terminal sequence of MyBP-C, including the first C2 repeat. It is followed by two internal peptides, one of 5 kD containing exclusively spacer sequences between the first and second C2 motifs, and a 95-kD fragment containing five C2 domains and three fibronectin type III motifs. The C-terminal sequence of MyBP-C is present in a 14-kD peptide which contains only the last C2 repeat. We examined the binding properties of these fragments to reconstituted (synthetic) myosin filaments. Only the COOH-terminal 14-kD peptide is capable of binding myosin with high affinity. The NH2-terminal 28-kD fragment has no myosin-binding, while the long internal 100-kD peptide shows very weak binding to myosin. We have expressed and purified the 14-kD peptide in Escherichia coli. The recombinant protein exhibits saturable binding to myosin with an affinity comparable to that of the 14-kD fragment obtained by proteolytic digestion (1/2 max binding at approximately 0.5 microM). These results indicate that the binding to myosin filaments is mainly restricted to the last 102 amino acids of MyBP-C. The remainder of the molecule (1,032 amino acids) could interact with titin, MyBP-H (H protein) or thin filament components. A comparison of the highly conserved Ig C2 domains present at the COOH-terminus of five MyBPs thus far sequenced (human slow and fast MyBP-C, human and chicken MyBP-H, and chicken MyBP-C) was used to identify residues unique to these myosin-binding Ig C2 repeats.

Identification of the A-band localization domain of myosin binding proteins C and H (MyBP-C, MyBP-H) in skeletal muscle

1999 ◽  
Vol 112 (1) ◽  
pp. 69-79 ◽  
Author(s):  
R. Gilbert ◽  
J.A. Cohen ◽  
S. Pardo ◽  
A. Basu ◽  
D.A. Fischman
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Binding Proteins ◽  
Thick Filament ◽  
Terminal Segment ◽  
Binding Domain ◽  
Striated Muscles ◽  
Fibronectin Type Iii ◽  
Chimeric Construct ◽  
Myosin Binding

Although major constituents of the thick filaments of vertebrate striated muscles, the myosin binding proteins (MyBP-C and MyBP-H) are still of uncertain function. Distributed in the cross-bridge bearing zone of the A-bands of myofibrils, in a series of transverse 43 nm stripes, the proteins are constructed of a tandem series of small globular domains, each composed of approximately 90–100 amino acids, which have sequence similarities to either the C2-set of immunoglobulins (IgC2) and the fibronectin type III (FnIII) motifs. MyBP-C is composed of ten globular domains (approximately 130 kDa) whereas MyBP-H is smaller (approximately 58 kDa) and consists of a unique N-terminal segment followed by four globular domains, the order of which is identical to that of MyBP-C (FnIII-IgC2-FnIII-IgC2). To improve our understanding of this protein family we have characterized the domains in each of these two proteins which are required for targeting the proteins to their native site(s) in the sarcomere during myogenesis. Cultures of skeletal muscle myoblasts were transfected with expression plasmids encoding mutant constructs of the MyBPs bearing an N-terminal myc epitope, and their localization to the A-band examined by immunofluorescence microscopy. Based on the clarity and intensity of the myc A-band signals we concluded that constructs encoding the four C-terminal motifs of MyBP-C and MyBP-H (approximately 360 amino acids) were all that was necessary to efficiently localize each of these peptides to the A-band. Truncation mutants lacking one of these 4 domains were less efficiently targeted to the C-zone of the sarcomere. Deletion of the last C-terminal motif of MyBP-H, its myosin binding domain, abolished all localization to the A-band. A chimeric construct, HU-3C10, in which the C-terminal motif of MyBP-H was replaced by the myosin binding domain of MyBP-C, efficiently localized to the A-band. Taken together, these observations indicate that MyBP-C and MyBP-H are localized to the A-band by the same C-terminal domain, composed of two IgC2 and two FnIII motifs. A model has been proposed for the interaction and positioning of the MyBPs in the thick filament through a ternary complex of the four C-terminal motifs with the myosin rods and titin.

scholarly journals Interaction of CREB and PGC-1α Induces Fibronectin Type III Domain-Containing Protein 5 Expression in C2C12 Myotubes

2018 ◽  
Vol 50 (4) ◽  
pp. 1574-1584 ◽  
Author(s):  
Xiu-ying Yang ◽  
Margaret C.L. Tse ◽  
Xiang Hu ◽  
Wei-hua Jia ◽  
Guan-hua Du ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Metabolic Effects ◽  
Hek293 Cells ◽  
Metabolic Phenotype ◽  
C2c12 Myotubes ◽  
Type Iii ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Fibronectin Type

Background/Aims: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. Methods: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). Results: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. Conclusion: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.

The carboxyl terminus of myosin binding protein C (MyBP-C, C-protein) specifies incorporation into the A-band of striated muscle

1996 ◽  
Vol 109 (1) ◽  
pp. 101-111 ◽  
Author(s):  
R. Gilbert ◽  
M.G. Kelly ◽  
T. Mikawa ◽  
D.A. Fischman
Keyword(s):  
Amino Acids ◽  
Protein C ◽  
Binding Protein ◽  
Thick Filament ◽  
Binding Domain ◽  
C Protein ◽  
Amino Terminal ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

Myosin binding protein-C (MyBP-C), also known as C-protein, is a major constituent of the thick filaments of vertebrate striated muscles. The protein, approximately 130 kDa, consists of a series of 10 globular motifs (numbered I to X) each of approximately 90–100 amino acids, bearing resemblance to the C2-set of immunoglobins (Ig C2) and to the fibronectin type III (FnIII) motifs. Using pure preparations of myosin and MyBP-C, it has been demonstrated that the major myosin binding domain of MyBP-C resides within the C-terminal Ig C2 motif (motif X). However, in the context of the in vivo thick filament, it is uncertain if the latter domain is sufficient to target MyBP-C correctly to the A-band or if other regions of the molecule are required for this process. To answer this question, cultures of skeletal muscle myoblasts were transfected with expression plasmids encoding seven truncation mutants of MyBP-C, and their targeting to the A-band investigated by immunofluorescence microscopy. To distinguish the recombinant proteins from endogenous MyBP-C, a myc epitope was inserted at each amino terminus. Recombinant MyBP-C exhibited an identical distribution in the sarcomere to that of native MyBP-C; i.e. it was found exclusively in the C-zone of the A-band. A mutant encoding the C-terminal 372 amino acids, but lacking motifs I-VI (termed delta 1–6), also targeted correctly to the A-band. This fragment, which is composed of two Ig C2 and two FnIII motifs, was the minimal protein fragment required for correct A-band incorporation. Larger amino-terminal deletions or deletion of motif X, the myosin binding domain, abolished all localization to the A-band. One construct (delta 10) lacking only motif X strongly inhibited myofibril assembly. We conclude that the myosin binding domain of MyBP-C, although essential, is not sufficient for correct incorporation into the A-band and that motifs VII to IX are required for this process. The data suggest a topological model in which MyBP-C is associated with the thick filament through its C terminus.

Mammalian skeletal muscle C-protein: purification from bovine muscle, binding to titin and the characterization of a full-length human cDNA

1992 ◽  
Vol 102 (4) ◽  
pp. 769-778
Author(s):  
D.O. Furst ◽  
U. Vinkemeier ◽  
K. Weber
Keyword(s):  
Skeletal Muscle ◽  
Protein Sequencing ◽  
Protein Isoforms ◽  
Fast Method ◽  
Mammalian Skeletal Muscle ◽  
Terminal Sequence ◽  
C Protein ◽  
Human Sequence ◽  
Associated Proteins ◽  
Bovine Skeletal Muscle

We report a fast method for the isolation of homogeneous C-protein from bovine skeletal muscle. In electron micrographs C-protein appears as short rods with a relatively uniform length of about 50 nm. Protein sequencing shows a single N-terminal sequence. Radio-labelled C-protein strongly decorates titin II and myosin rods but not myosin heads. Binding to titin II is retained in preparations lacking titin-associated proteins. Antibodies to bovine C-protein were used to screen a lambda gt11 cDNA library constructed from fetal human skeletal muscle. Clone HC38 is 3833 bp long and encodes a protein of 1138 amino acid residues. The start of the predicted sequence fits the N-terminal sequence of the bovine protein. All partial sequences obtained from the bovine protein (348 residues) and the sequence deduced from a partial chicken cDNA (Einheber and Fischman, 1990) can be aligned along the human sequence. The sequences of human and chicken C-proteins share 50% identity and 70% similarity. Along the repeat patterns of the human protein the fibronectin (Fn)-like domains are better conserved than the immunoglobulin (Ig)-like domains. Regions of strong divergence between chicken fast C-protein and human slow C-protein may represent differences in C-protein isoforms.

scholarly journals Cloning and characterization of R-PTP-kappa, a new member of the receptor protein tyrosine phosphatase family with a proteolytically cleaved cellular adhesion molecule-like extracellular region.

1993 ◽  
Vol 13 (5) ◽  
pp. 2942-2951 ◽  
Author(s):  
Y P Jiang ◽  
H Wang ◽  
P D'Eustachio ◽  
J M Musacchio ◽  
J Schlessinger ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Precursor Protein ◽  
Receptor Protein ◽  
Protein Tyrosine ◽  
Type Iii ◽  
Receptor Protein Tyrosine Phosphatase ◽  
Fibronectin Type Iii ◽  
Fibronectin Type

We describe a new member of the receptor protein tyrosine phosphatase family, R-PTP-kappa, cDNA cloning predicts that R-PTP-kappa is synthesized from a precursor protein of 1,457 amino acids. Its intracellular domain displays the classical tandemly repeated protein tyrosine phosphatase homology, separated from the transmembrane segment by an uncharacteristically large juxta-membrane region. The extracellular domain of the R-PTP-kappa precursor protein contains an immunoglobulin-like domain and four fibronectin type III-like repeats, preceded by a signal peptide and a region of about 150 amino acids with similarity to the Xenopus A5 antigen, a putative neuronal recognition molecule (S. Takagi, T. Hsrata, K. Agata, M. Mochii, G. Eguchi, and H. Fujisawa, Neuron 7:295-307, 1991). Antibodies directed against the intra- and extracellular domains reveal that the R-PTP-kappa precursor protein undergoes proteolytic processing, following which both cleavage products remain associated. By site-directed mutagenesis, the likely cleavage site was shown to be a consensus sequence for cleavage by the processing endopeptidase furin, located in the fourth fibronectin type III-like repeat. In situ hybridization analysis indicates that expression of R-PTP-kappa in the central nervous system is developmentally regulated, with highest expression seen in actively developing areas and, in the adult, in areas capable of developmental plasticity such as the hippocampal formation and cerebral cortex. The mouse R-PTP-kappa gene maps to chromosome 10, at approximately 21 centimorgans from the centromere.

Cloning and characterization of R-PTP-kappa, a new member of the receptor protein tyrosine phosphatase family with a proteolytically cleaved cellular adhesion molecule-like extracellular region

1993 ◽  
Vol 13 (5) ◽  
pp. 2942-2951
Author(s):  
Y P Jiang ◽  
H Wang ◽  
P D'Eustachio ◽  
J M Musacchio ◽  
J Schlessinger ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Precursor Protein ◽  
Receptor Protein ◽  
Protein Tyrosine ◽  
Type Iii ◽  
Receptor Protein Tyrosine Phosphatase ◽  
Fibronectin Type Iii ◽  
Fibronectin Type

We describe a new member of the receptor protein tyrosine phosphatase family, R-PTP-kappa, cDNA cloning predicts that R-PTP-kappa is synthesized from a precursor protein of 1,457 amino acids. Its intracellular domain displays the classical tandemly repeated protein tyrosine phosphatase homology, separated from the transmembrane segment by an uncharacteristically large juxta-membrane region. The extracellular domain of the R-PTP-kappa precursor protein contains an immunoglobulin-like domain and four fibronectin type III-like repeats, preceded by a signal peptide and a region of about 150 amino acids with similarity to the Xenopus A5 antigen, a putative neuronal recognition molecule (S. Takagi, T. Hsrata, K. Agata, M. Mochii, G. Eguchi, and H. Fujisawa, Neuron 7:295-307, 1991). Antibodies directed against the intra- and extracellular domains reveal that the R-PTP-kappa precursor protein undergoes proteolytic processing, following which both cleavage products remain associated. By site-directed mutagenesis, the likely cleavage site was shown to be a consensus sequence for cleavage by the processing endopeptidase furin, located in the fourth fibronectin type III-like repeat. In situ hybridization analysis indicates that expression of R-PTP-kappa in the central nervous system is developmentally regulated, with highest expression seen in actively developing areas and, in the adult, in areas capable of developmental plasticity such as the hippocampal formation and cerebral cortex. The mouse R-PTP-kappa gene maps to chromosome 10, at approximately 21 centimorgans from the centromere.

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