title: Characterization of a novel 550-kDa protein in skeletal muscle of chick embryo.
abstract: Some characteristics of a novel 550-kDa protein which is abundant in skeletal muscle tissues at an early stage of the chick embryo, and localized in the peripheries of adult muscle fibers and at the Z-disks of isolated myofibrils, was investigated. A cosedimentation experiment and solid phase immunoabsorbent assay showed that the 550-kDa protein binds directly to F-actin. Therefore, it is concluded that the 550-kDa protein is a novel actin-binding protein. The 550-kDa protein was also interacted with alpha-actinin, laminin, fibronectin and Type IV collagen. Reactions with several kinds of lectin revealed that the 550-kDa protein is a glycoprotein containing oligosaccharides. Electron microscopic observation of negatively stained 550-kDa protein showed that native 550-kDa protein molecules are particles with an average diameter of 26.5 nm, but those particles treated with ethanol/ether are filamentous structures. These results suggest that the 550-kDa protein in the cytoplasma of unorganized skeletal muscle tissues exists as lipid-protein complex. Consequently, the 550-kDa protein may play an important role in the binding of myofibrils to the basal lamina by interaction with F-actin, alpha-actinin, laminin, fibronectin or Type IV collagen.
mesh_terms: D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002642:Chick Embryo; D004797:Enzyme-Linked Immunosorbent Assay; D005353:Fibronectins / Q000378:metabolism; D006023:Glycoproteins / Q000032:analysis; D007163:Immunosorbent Techniques; D007797:Laminin / Q000378:metabolism; D008854:Microscopy, Electron; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000196:embryology*; D009844:Oligosaccharides / Q000032:analysis; D014018:Tissue Distribution
chemical_list: D000199:Actins; D005353:Fibronectins; D006023:Glycoproteins; D007797:Laminin; D009124:Muscle Proteins; D009844:Oligosaccharides; D000185:Actinin