Solubility in non-ionic detergents distinguishes between slowly and rapidly degraded plasma membrane proteins

Abstract

Four cell surface-exposed, integral membrane proteins from H4-II-E-3 hepatoma monolayer cultures, derivatized by the membrane-impermeant reagent sulfosuccinimidyl 2-(biotin-amido)ethyl-1,3-dithioproprionate, were resistant to extraction with Triton X-100 at 0 degrees C. Thirty-three other similarly derivatized proteins were solubilized under these same conditions. Antisera were prepared that reacted only with Triton X-100-insoluble proteins. All four Triton X-100-insoluble proteins precipitated with the antibody were slowly degraded (t1/2 > 100 h). By contrast, all but four Triton X-100-soluble proteins were rapidly degraded (t1/2 = 24 h). The detergent-insoluble proteins did not possess glycosylphosphatidylinositol anchors nor were they solubilized by Triton X-100 after disruption of the cytoskeleton. In addition, they were insoluble in Triton X-100 in isolated membrane preparations but soluble when isolated on streptavidin-agarose and removed from other membrane proteins. We conclude that protein-protein interactions within the membrane itself result in insolubility in non-ionic detergents for a small cohort of plasma membrane proteins and that this may be directly related to the increased metabolic stability for this class of proteins.