Characterization of a 140Kd cell surface glycoprotein involved in myoblast adhesion

Abstract

Two monoclonal antibodies that cause changes in the morphology of cultured chick myogenic cells have been described previously [8]. In this paper, these antibodies are shown to interact with the same 140Kd protein. The 140Kd protein has been further characterized as a cell-surface glycoprotein by lactoperoxidase-catalyzed iodinations and lectin affinity chromatography. The protein is resistant to digestion by trypsin and collagenase and has been shown to be unrelated to fibronectin by immunoprecipitation studies and by peptide mapping. A second protein, of approximately 170Kd MW, is also immunoprecipitated by the monoclonal antibodies. This protein is probably unrelated to the 140Kd protein since the peptide maps are quite distinct.

An integral membrane protein antigen associated with the membrane attachment sites of actin microfilaments is identified as an integrin beta-chain.

“…2C and D), but different from the maps of the 110-kDa proteins. As suggested elsewhere (3,16), the 170-kDa protein is therefore immunochemically and structurally probably not related to the 110-kDa protein but is very likely complexed to it in the membrane, the complex resisting dissociation upon NP-40 solubilization. The results are consistent with the conclusion that the same complex is immunoadsorbed by both MAbs 30B6 and JG9.…”

“…Our results indicate that MAb 30B6, produced in response to immunization with intact mitotic CEFs and selected for its immunofluorescent localization to the actin microfilamentenriched cleavage furrow of the dividing cells (16), and the separately derived MAbs JG9 and JG22, produced in response to immunization with chicken embryo myoblast preparations and selected for their capacity to inhibit or disrupt myoblast attachment to their substrate (7) and which recognize the same antigen (3,7), are all directed to the same, or a closely similar, cell surface integral membrane protein.…”

“…These MAbs include JG9 and JG22, derived by Greve and Gottlieb (7), and CSAT, produced by Neff et al (14). MAbs JG22 and JG9 were shown to react with the same antigen (3,7). MAb JG22 was found to immunoprecipitate or immunoadsorb a set of three proteins of about 160, 140, and 120 kDa from extracts of whole chicken embryos (5).…”

Disialoganglioside GD2 distributes preferentially into substrate-associated microprocesses on human melanoma cells during their attachment to fibronectin.

“…In a previous paper, we used monoclonal antibodies (Mabs) ~ that specifically recognize carbohydrate determinants on the gangliosides GD2 and GD32 (8) to localize them on the surface of human melanoma cells and their focal adhesion plaques. The contention that gangliosides are indeed important molecules in cell-substratum interactions is strengthened by the fact that pretreatment of melanoma cells with specific Mabs directed to either GD2 or GD3 significantly decreased their ability to attach and spread on a variety of extracellular matrix proteins, which include fibronectin, vitronectin, laminin, and collagen (10).The attachment and spreading of cells on extracellular matrix components undoubtedly involve very complex interactions which include not only specific receptors (1,4,5,13,15, 27, 31,33,45,46) on the surface of the membrane but also cytoskeletal components beneath it (22,35,36). Components of substrate-attached cell adhesion plaques include cytoskeletal proteins (22, 35, 36) and proteoglycans (14, 21, …”

“…The attachment and spreading of cells on extracellular matrix components undoubtedly involve very complex interactions which include not only specific receptors (1,4,5,13,15,27,31,33,45,46) on the surface of the membrane but also cytoskeletal components beneath it (22,35,36). Components of substrate-attached cell adhesion plaques include cytoskeletal proteins (22,35,36) and proteoglycans (14, 21, I.…”