The first step of laminin 1-induced signal transduction is initiated by the formation of alpha 6 beta 1 integrin-specific adhesion complexes. In contrast, on other laminin isoforms the adhesion complexes are alpha 3 beta 1 integrin-specific due to a transdominant regulation of the alpha 6 beta 1 integrin by the alpha 3 beta 1 integrin. To determine the mechanism of this regulation, peptides representing the cytoplasmic domain of the alpha 3 or alpha 6 integrin subunits were microinjected together with recombinant enhanced green fluorescence protein into live fibroblasts. Microinjection of the alpha 3 integrin peptide to laminin 1-adherent cells displaying alpha 6 beta 1 integrin-specific adhesion complexes resulted in the disengagement of the alpha 6 beta 1 integrin, while microinjection of green fluorescence protein alone or in combination with the alpha 6 integrin cytodomain had no effect. Further surface plasmon resonance studies revealed that the cytodomain of the beta 1 integrin subunit interacts with low affinity with the cytoplasmic tail of the alpha 3 integrin subunit, but not with that of several other alpha subunits including alpha 6. These results imply that the cytoplasmic tails of the integrin alpha subunits play a critical role in the regulation of integrin-induced signal transduction. In particular, the intracellular tail of the alpha 3 integrin subunit controls the formation of adhesion complexes in cells adhering to laminins.
Interaction between the cytodomains of the alpha 3 and beta 1 integrin subunits regulates remodelling of adhesion complexes on laminin
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E. Laplantine, L. Vallar, K. Mann, N. Kieffer, M. Aumailley; Interaction between the cytodomains of the alpha 3 and beta 1 integrin subunits regulates remodelling of adhesion complexes on laminin. J Cell Sci 1 April 2000; 113 (7): 1167–1176. doi: https://doi.org/10.1242/jcs.113.7.1167
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