Basolateral targeting and efficient consumption of transforming growth factor-alpha when expressed in Madin-Darby canine kidney cells.

摘要: To investigate the trafficking of transforming growth factor-alpha precursor (pro-TGF-alpha) in polarized epithelial cells, wild type and membrane-fixed human pro-TGF-alpha were introduced into Madin-Darby canine kidney (MDCK) cells. We show that was synthesized processed normally to release mature 5.6-kDa TGF-alpha basal medium while remained cell-associated. Antibody (mAb-528) receptor blockade experiments demonstrated efficient consumption basally released by basolateral epidermal factor receptors, indicating can act an autocrine manner these Biochemical analysis showed expressed on surface as either a 17- or 30-kDa species; 17-kDa forms both constructs had basolateral/apical ratios > 20:1. By confocal microscopy, immunolocalized lateral membrane surfaces. In pulse-chase combined with cell immunoprecipitation, we newly are delivered directly 94 96% efficiency, respectively. These results also provide direct evidence for sequential cleavage at surface. Thus, is sorted intracellularly vectorially targeted domain The MDCK line provides ideal vitro model examine molecular basis other factor-like factors cells their potential interactions receptors.