PREFERENTIAL ASSOCIATION OF MEMBRANE PHOSPHOLIPIDS WITH THE HUMAN ERYTHROCYTE HEXOSE TRANSPORTER

This study reports the results of an investigation to determine to wha t extent the influence of membrane lipids on the human erythrocyte sug ar transporter protein activity (Caruthers, A, and Melchior, D.L. (198 8) Annu, Rev. Physiol. 50, 257-271) is related to lipid/protein associ ations in the membrane bilayer. Differential scanning calorimetry was carried out on the human erythrocyte transport protein reconstituted i nto artificial bilayers formed from preselected lipids. It was found t hat the transport protein displays a preferential and in some cases st rongly preferential affinity for specific lipid types. This associatio n is a function of lipid head group, backbone and hydrocarbon chain le ngth. It appears that the affinity of the transport protein for variou s lipids can correlate with the lipid's ability to influence transport er activity. This study further suggests that certain lipids (in this case sphingomyelin) can induce an oligomeric association of HEST monom ers in the bilayer.