THE ALPHA-6-BETA-1 (VLA-6) AND ALPHA-6-BETA-4 PROTEIN COMPLEXES - TISSUE DISTRIBUTION AND BIOCHEMICAL-PROPERTIES

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  • 1 June 1990
    • journal article
    • research article
    • Vol. 96, 207-217
Abstract
A member of the integrin family, the .alpha.6/.beta.4 complex was previously identified on human and mouse carcinoma cell lines by using a rat monoclonal antibody to .beta.6. Here we describe two monoclonal antibodies that recognize epitopes on the .beta.4 subunit of the human and mouse .alpha.6.beta.4 complexes. The monoclonal antibodies against .beta. were able to preclear .alpha.6.beta.4, but not .alpha.6.beta.1 from cell line extracts. A substantial fraction of the total .beta.4 subunits present on the cell surface was not associated with .alpha.6, as it could not be removed by anti-.alpha.6 antibodies, but remained precipitable with anti-.beta.4 antibodies. There was no evidences for novel .alpha. subunits associated with .beta.4. The .alpha.6 subunit consists of disulfide-linked heavy and light chains. The variability in size of these two chains from different cell types is largely due to differences in modifications of N-linked glycans. Additional heterogeneity may be caused by differential proteolytic cleavage of the .alpha.6 precursor. Immunoperoxidase staining of tissue sections neonatal and adult mice revealed that .beta.4 expression is limited to epithelial tissues and peripheral nerves. The .alpha.6 subunit has a wider distribution that includes all tissues and cells stained by antibodies against .beta.4. Cells and tissue that are positive for .alpha.6, but negative for .beta.4. Cells and tissue that are positive for .alpha.6, but negative for .beta.4, may express the .alpha.6.beta.1 complex.

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