STABLE EXPRESSION OF VLA-4 AND INCREASED MATURATION OF THE BETA(1)-INTEGRIN PRECURSOR AFTER TRANSFECTION OF CHO CELLS WITH ALPHA(4M) CDNA

A full-length cDNA coding for the murine alpha(4) integrin subunit (al pha(4m)) was transfected into CHO-K1 cells and cell lines that express ed VLA4 at their surface as a result of the association of transfected alpha(4m) with endogenous hamster beta(1) were selected. Functionalit y of the expressed alpha(4m)beta(1) was shown by adhesion assays on VC AM-1 and antibody (anti-VCAM-1) inhibition. Pulse chase experiments in dicated that transfection of the murine alpha(4) cDNA into CHO cells l ed to an increase in maturation and a decrease in degradation of the b eta(1) precursor subunit compared to control CHO-K1 cells. This was su pported by FACS analysis, using an anti-hamster beta(1) monoclonal ant ibody, which showed that more B-1 subunit was expressed at the surface of these stably transfected alpha(4m) expressing cells. These results support the hypothesis that degradation of precursor beta(1) is at le ast partly determined by the quantity of a subunits available intracel lulary for heterodimer formation.