ABSTRACT
Background. Specific antibodies for human IFNç-R1 were used to examine its mobilization in Colo 205 cells. Methods. We report here that antibody-IFNç-R1 complex induced capping and actin colocalization. Pretreatment witrh cytochalasin D abolished this capping. To define the role of the IFNç-R1 in the possible interaction with actin, transfected murine fibroblasts cell line with human cDNA IFNç-R1 were used. Results. Only those cells expressing the full receptor and cultured in suspension polarized the receptor and this colocalized with actin filaments. Nevertheless, cells truncated in their intracellular domain displayed no capping and actin remained unaltered either in suspension or in monolayer culture conditions. As mutant bearing an IFNç-R1 with substitutions in positions 270-271 of the intracellular domain redistributed both IFNç-R1 and actin as micropatches instead of capping. Mutation in 256-303 residues resulted in IFNç-R1 microaggregates but actin remained unchanged. Conclusions. These experimental models allowed us to highlight an apparent receptormicrofilament association through the intracellular domain of IFNç-R1, and to specifically locate it within the intracellular region 256-303 that has been identified as relevant for ligand-receptor internalization and biological function