Mechanisms of Active Transport in Isolated Membrane Vesicles

Abstract

Membrane Preparations-E.coli ML 308-225l (i-z-y+af) was grown on llIedium A (3) containing 1 yc disodium succinate (hesahydrate) ; E. coli ML 301 (i+z+y+a+) on Medium A containing 0.5yG glucuronic acid or arabinose as indicated; E. cola on Medium A containing 0.5% galactose; and E. coli GN-22 (i-z+y+a+; enzyme I-) on Medium 63 (4) containing 0.2% glucose-6-P.Membrane vesicles were prepared from these cells as described previously (5-7).Transport Studies-Assays for lactose and amino acid uptake were carried out as reported previously (7-Q).Glucuronate, arabinose, galactose, and glucose-6-P uptake studies were performed exactly as described for lactose and amino acid uptake with final concentrations of glucuronate, arabinose, galactose, and glucose-6-P of 0.1,0.3,0.2, and 0.02 mu, respectively.1 These strains were obtained from Dr. T. H. Wilson.