Partial purification of alanine carrier from rabbit small intestine brush border membrane and its functional reconstitution into proteoliposomes

An alanine transport carrier was partially purified from brush border membranes of rabbit small intestine. The alanine carrier activity was not solubilized with 0.4% deoxycholate but recovered in the detergent-insoluble fraction. The detergent-insoluble proteins were reconstituted into proteoliposomes with soybean phospholipids. The reconstituted proteoliposomes were capable of uptake of alanine driven by an electrochemical potential of Na+. The initial rate of alanine uptake into the proteoliposomes was 90 pmoles/mg protein/sec, which was 15-fold higher than that observed with the native membrane vesicles. The uptake of alanine was effectively suppressed by various neutral amino acids but not by either cationic or anionic amino acids.