H-2 histocompatibility antigens of subcellular membranes of mouse liver

Abstract

Purified fractions of plasma membrane, Golgi apparatus, rough endoplasmic reticulum vesicles, nuclear envelope, and mitochondria were isolated from mouse liver and the distribution of H-2 histocompatibility antigens determined by indirect radioimmunoassay before and after membrane disruptive treatments. Fractions enriched in plasma membrane (surface membrane) revealed H-2 antigens in highest concentration; disruptive treatments were not necessary to reveal H-2 antigens with surface membranes. In contrast, internal membranes did not possess H-2 antigens which were accessible to antibody. Golgi apparatus fractions or some component of these fractions (e.g. secretory vesicles) possessed the antigens but in a latent form where accessibility was provided by simple rupture of the membrane vesicles. With endoplasmic reticulum, detergent solubilization of the membranes was required before H-2 antigen could be detected. Nuclear envelope preparations contained little or no demonstrable H-2 activity. These results were confirmed by several techniques including immunoprecipitation of labelled solubilized membrane components with anti-H-2 serum and subsequent analysis in SDS-PAGE.