The nonintegrin laminin binding protein (p67 LBP) is expressed on a subset of activated human T lymphocytes and, together with the integrin very late activation antigen-6, mediates avid cellular adherence to laminin.
A search for genes expressed in activated T cells revealed that the nonintegrin, 67-kDa laminin binding protein (p67 LBP) is expressed on the surface of a subset (10-15%) of activated peripheral blood T cells. Surface p67 LBP expression is detectable by FACS using the anti-p67 LBP mAb, MLuC5, within 6 h of T cell activation with phorbol dibutyrate and ionomycin, peaks 18-36 h postactivation, and persists for 7-10 days. The subset of T cells expressing p67 LBP is composed of mature, single-positive cells (85% CD4+8-, 15% CD4-8+) of memory cell phenotype (100% CD45 RO+/CD45 RA-). The p67 LBP+ T cells also express the integrin alpha6 chain (CD49f), which is known to associate with p67 LBP on tumor cells. In addition, the p67 LBP+ T cells express the integrin beta1, which associates with alpha6 in the laminin-specific integrin receptor very late activation Ag (VLA)-6 (alpha6beta1). Expression of an exogenous cDNA encoding the 37-kDa LBP precursor (p37 LBPP) confers p67 LBP surface expression on a p67 LBP-negative Jurkat T cell line (B2.7). Expression of p67 LBP induces B2.7 transfectants to adhere to laminin, but avid laminin binding depends on coexpression of VLA-6. Taken together, these data indicate that p67 LBP is an activation-induced surface structure on memory T cells that, together with VLA-6, mediates cellular adherence to laminin.
Canfield
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SM
Laboratory of Molecular Immunology, Department of Medicine, Columbia University, New York 10032, USA. smc12@columbia.edu
Khakoo
A Y
AY
D002448:Cell Adhesion / Q000276:immunology; D002999:Clone Cells; D018076:DNA, Complementary / Q000096:biosynthesis; D006801:Humans; D039121:Integrin alpha6beta1; D016023:Integrins / Q000502:physiology*; D019169:Jurkat Cells; D007797:Laminin / Q000378:metabolism*; D008213:Lymphocyte Activation; D008970:Molecular Weight; D011498:Protein Precursors / Q000096:biosynthesis* / Q000502:physiology; D017474:Receptors, Laminin / Q000502:physiology*; D016176:T-Lymphocyte Subsets / Q000378:metabolism* / Q000502:physiology; D014162:Transfection
D018076:DNA, Complementary; D039121:Integrin alpha6beta1; D016023:Integrins; D007797:Laminin; D011498:Protein Precursors; D017474:Receptors, Laminin