Flow kinetics of mouse histocompatibility antigens.

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Abstract
Major histocompatibility antigens of the mouse (H-2 antigens) are found on a variety of different cell types and constitute a class of integral membrane-bound glycoproteins involved in tissue graft rejection and immune surveillance. Monospecific alloantibodies directed against mouse H-2 antigens and standard pulse-chase technique were used to investigate the flow kinetics of delivery of newly synthesized membrane constituents to the cell surface. [35S]Methionine was injected i.p., after a chase with unlabeled methionine, livers were excised and fractionated into endoplasmic reticulum, Golgi apparatus and plasma membrane fractions. Label first appeared in H-2 antigens located within the endoplasmic reticulum. Maximum specific activity observed between 5-7 min after injection of label was followed by a rapid loss of label. H-2 antigens of Golgi apparatus also were labeled early. Peak specific activity observed 15-25 min f after injection of label was again followed by rapid loss of label. H-2 antigens of the plasma membrane were labeled last and appeared to accumulate radioactivity with no evidence of rapid turnover. Evidence for a precursor-product relationship between H-2 antigens located within the cell on membranes of endoplasmic reticulum and Golgi apparatus and those on the plasma membrane was provided. Flow of individual membrane-bound glycoproteins from their sites of synthesis and insertion into the membrane of the endoplasmic reticulum to the plasma membrane through the Golgi apparatus is indicated.