Related Experiment Videos
Control of beta1 integrin function. Localization of stimulatory epitopes
J A Wilkins1, A Li, H Ni
1Rheumatic Disease Unit Research Laboratory, Department of Internal Medicine, University of Manitoba, Winnipeg MB R3A 1M4, Canada.
The beta1 integrins can be expressed on the surface of cells in a latent form, which is activated by a variety of stimuli. As an approach to examining the transition to an active receptor, a panel of stimulatory antibodies to beta1 were produced and characterized. These antibodies induced adherence of the T-leukemic cell line Jurkat to collagen and fibronectin. Competitive antibody binding assays indicated the existence of at least three distinct epitope clusters A (B3B11, JB1B, 21C8), B (B44, 13B9), and C(N29) defined by the indicated antibodies. Two antibodies to the A site, JB1B and B3B11, were shown to localize to positions 671-703 and 657-670, respectively, of the beta1. This region is located in an area encompassing a predicted disulfide bond between linearly distant cysteines in beta1 (Cys415-Cys671). The homologous region of the beta3 integrin (490 690 and 602 690) has been shown to be one of the sites recognized by stimulatory antibodies to ligand-induced binding sites. The present results indicate the existence of multiple stimulatory regions and suggest considerable homology between the locations of beta1 and beta3 regulatory sites.
The beta1 integrins can be expressed on the surface of cells in a latent form, which is activated by a variety of stimuli. As an approach to examining the transition to an active receptor, a panel of stimulatory antibodies to beta1 were produced and characterized. These antibodies induced adherence of the T-leukemic cell line Jurkat to collagen and fibronectin. Competitive antibody binding assays indicated the existence of at least three distinct epitope clusters A (B3B11, JB1B, 21C8), B (B44, 13B9), and C(N29) defined by the indicated antibodies. Two antibodies to the A site, JB1B and B3B11, were shown to localize to positions 671-703 and 657-670, respectively, of the beta1. This region is located in an area encompassing a predicted disulfide bond between linearly distant cysteines in beta1 (Cys415-Cys671). The homologous region of the beta3 integrin (490 690 and 602 690) has been shown to be one of the sites recognized by stimulatory antibodies to ligand-induced binding sites. The present results indicate the existence of multiple stimulatory regions and suggest considerable homology between the locations of beta1 and beta3 regulatory sites.