期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1983
卷号：80
期号：2
页码：430-434
DOI：10.1073/pnas.80.2.430
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The molecular nature of the cell surface-cytoskeleton interaction in microvilli isolated from ascites 13762 rat mammary adenocarcinoma sublines with immobile (MAT-C1) and mobile (MAT-B1) receptors was investigated by extraction and fractionation studies on the microvillar membranes. Extraction of membranes from MAT-C1 cells with Triton X-100-containing buffers gave insoluble residues showing three major components by NaDodSO4/polyacrylamide gel electrophoresis: actin, a 58,000-dalton polypeptide, and a cell surface glycoprotein of 75,000-80,000 daltons. The ratio of these components in Triton X-100-insoluble residues, as determined by scintillation counting of bands from gels of [3H]leucine-labeled microvillar membranes, approached equimolar, suggesting a specific complex of the components. The three components of the putative complex cosedimented on sucrose density gradients of Triton X-100/buffer-treated membranes. Gel filtration on Sepharose 2B gave a peak included in the column that contained only the glycoprotein, actin, and 58,000-dalton polypeptide by one-dimensional NaDodSO4 electrophoresis and by two-dimensional isoelectric focusing/NaDodSO4 electrophoresis. The glycoprotein-actin association could be disrupted only under strongly denaturing conditions. Complex prepared from MAT-B1 microvillar membranes by Sepharose 2B gel filtration in Triton X-100-containing buffers contained actin and the glycoprotein but no 58,000-dalton polypeptide. From these results we propose that the cell surface-cytoskeleton interactions in the 13762 tumor cell microvilli involve direct association of actin with the cell surface glycoprotein. We further suggest that the 58,000-dalton polypeptide stabilizes the association of this complex with the microfilaments in the MAT-C1 microvilli, thereby stabilizing the microvilli and restricting cell surface receptor mobility.
