EFFECT OF PURIFICATION PROTOCOL ON THE FUNCTIONAL-PROPERTIES OF ERYTHROCYTE-MEMBRANE PROTEIN-4.1

The inositol hexaphosphate (IHP) method for purification of the erythr ocyte membrane protein 4.1 yields the largest quantity of pure protein of any published protocol. However, protein 4.1 isolated by this meth od was found to bind to RI-stripped inside-out red blood cell membrane vesicles (KIOVs) only 40% as well as protein 4.1 purified by other me thods. While an improved Tyler method, the SP method, yields 30-40% le ss protein 4.1 than the IHP method, the SP preparation nevertheless ex ceeds the IHP method in that the protein 4.1 is fully functional. Unli ke the Tyler method, the SP procedure is also free of contaminating sp ectrin, p55, and proteases. (C) 1998 Academic Press.