PMID: 9548475Apr 21, 1998Paper

Structural requirements for beta1 integrin-mediated tyrosine phosphorylation in human T cells

The Journal of Immunology : Official Journal of the American Association of Immunologists
L D FinkelsteinY Shimizu

Abstract

The beta1 integrin adhesion receptors activate signal transduction pathways that induce tyrosine phosphorylation of a variety of substrates. Increased tyrosine phosphorylation is mediated by the beta1 subunit cytoplasmic domain, which consists of 46 amino acids and contains no intrinsic kinase activity. In the H9 T cell line, beta1 integrin engagement leads to the increased tyrosine phosphorylation of three 105 to 115-kDa substrates that are distinct from focal adhesion kinase (FAK): HEF1 (human enhancer of filamentation 1), a protein with structural homology to p130Cas, and two novel substrates, pp105 and pp115. DNA-mediated gene transfer was used to explore the role of the beta1 cytoplasmic domain in integrin-mediated tyrosine phosphorylation of HEF1, pp105, and pp115 in human T cells. Using a chimeric receptor composed of the cytoplasmic domain of the beta1 integrin subunit and the extracellular and transmembrane domains of the CD2 Ag, we demonstrate that the beta1 cytoplasmic domain is necessary and sufficient for inducing tyrosine phosphorylation of each of these three substrates in H9 T cells. Analysis of a series of beta1 cytoplasmic domain truncations reveals that a truncation of only five amino acids from the carboxyl-...Continue Reading

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