Related Experiment Video
Updated: Aug 17, 2026
Isolation of Embryonic Tissues and Formation of Quail-Chicken Chimeric Organs Using The Thymus Example
Published on: February 16, 2019
Complete primary structure and tissue expression of chicken pectoralis M-protein
J Noguchi1, M Yanagisawa, M Imamura
1Institute of Basic Medical Sciences, University of Tsukuba, Ibaraki, Japan.
Abstract:
M-Protein (165 kDa) is a structural constituent of myofibrillar M-band in striated muscle. We generated a monoclonal antibody which recognized a 165-kDa protein from chicken pectoralis muscle in immunoblot analysis and stained the M-band under immunofluorescence microscopy. By screening a lambda gt11 cDNA library from chicken embryonic pectoralis muscle with this antibody, we isolated a cDNA clone encoding the M-protein. Northern blot analysis showed that M-protein mRNA is expressed in pectoralis and cardiac muscle but not in gizzard smooth muscle or non-muscle tissues. Moreover, the anterior latissimus dorsi muscle, which consists almost exclusively of slow fiber types, contains no detectable levels of the mRNA. The full-length cDNA sequence predicted a 1,450-amino acid polypeptide with a calculated molecular weight of 163 x 10(3). The encoded protein contains several copies of two different repetitive motifs: five copies of fibronectin type III repeats are in the middle part of the predicted molecule, and two and four copies of the immunoglobulin C2-type repeats are located toward the NH2-terminal and COOH-terminal regions, respectively. This indicates that M-protein, along with other thick filament-associated proteins such as C-protein, twichin, and titin, belongs to the superfamily of cytoskeletal proteins with immunoglobulin/fibronectin repeats.
Insights
Researchers identified chicken M-protein, a structural component of muscle M-bands. This protein, crucial for striated muscle, contains fibronectin and immunoglobulin repeats, classifying it with cytoskeletal proteins.
Area of Science:
- Muscle biology
- Molecular and cellular biology
Background:
- M-Protein is a 165 kDa structural component of the myofibrillar M-band in striated muscle.
- Understanding M-Protein's structure and expression is key to muscle function research.
Purpose of the Study:
- To isolate and characterize the chicken M-protein.
- To investigate the expression patterns of M-protein mRNA in different muscle tissues.
Main Methods:
- Generation of a monoclonal antibody against M-Protein.
- Screening of a chicken embryonic pectoralis muscle cDNA library.
- Immunoblot analysis, immunofluorescence microscopy, and Northern blot analysis.
Main Results:
- A monoclonal antibody recognized a 165 kDa protein and stained the M-band.
- A cDNA clone encoding M-protein was isolated, predicting a 1,450-amino acid polypeptide.
- M-protein mRNA expression was detected in pectoralis and cardiac muscle, but not in smooth muscle or non-muscle tissues, nor in slow-fiber dominant anterior latissimus dorsi muscle.
- The M-protein sequence revealed multiple fibronectin type III and immunoglobulin C2-type repeats.
Conclusions:
- M-protein is a striated muscle-specific protein.
- The presence of fibronectin and immunoglobulin repeats suggests M-protein belongs to a superfamily of cytoskeletal proteins.
