Muscle Organization in Caenorhabditis elegans: Localization of Proteins Implicated in Thin Filament Attachment and I-Band Organization

• Published in: The Journal of cell biology Vol. 101; no. 4; pp. 1532 - 1549
• Main Authors: Francis, G. Ross, Waterston, Robert H.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01-10-1985; The Rockefeller University Press
• Subjects: Actinin - immunology; Animals; Antibodies; Antibodies, Monoclonal - immunology; Antibody Specificity; Antigens; Biochemistry. Physiology. Immunology. Molecular biology; Biological and medical sciences; Caenorhabditis - anatomy & histology; Cell lines; Cell membranes; Epitopes - immunology; Fluorescence; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Gels; Integument; Invertebrates; Monoclonal antibodies; Muscle Proteins - immunology; Muscle Proteins - isolation & purification; Muscles; Muscles - analysis; Muscles - ultrastructure; Nemathelminthia. Plathelmintha; Nematodes; Peptides - immunology; Physiology. Development; Rabbits; Sarcomeres - analysis; Sarcomeres - ultrastructure; Proteins; Ultrastructure; Helmintha; Nemathelminthia; Muscle; Invertebrata; Nematoda
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.101.4.1532

The body wall muscle cells of Caenorhabitis elegans contain an obliquely striated myofibrillar lattice that is associated with the cell membrane through two structures: an M-line analogue in the A-band and a Z-disc analogue, or dense-body, in the I-band. By using a fraction enriched in these structures as an immunogen for hybridoma production, we prepared monoclonal antibodies that identify four components of the I-band as determined by immunofluorescence and Western transfer analysis. A major constituent of the dense-body is a 107,000-D polypeptide that shares determinants with vertebrate α-actinin. A second dense-body constituent is a more basic and antigenically distinct 107,000-D polypeptide that is localized to a narrow domain of the dense-body at or subjacent to the plasma membrane. This basic dense-body polypeptide is also found at certain cell boundaries where thin filaments in half-bands terminate at membrane-associated structures termed attachment plaques. A third, unidentified antigen is also found closely apposed to the cell membrane in regions of not only the dense-body and attachment plaque, but also the M-line analogue. Finally, a fourth high molecular weight antigen, composed of two polypeptides of ∼400,000-D, is localized to the I-band regions surrounding the dense-body. The attachment of the dense-body to the cell surface and the differential localization of the dense-body-associated antigens suggest a model for their organization in which the unidentified antigen is a cell surface component, and the two 107,000-D polypeptides define different cytoplasmic domains of the dense-body.