DIFFERENTIAL SECRETION OF ALPHA-1-ACID GLYCOPROTEIN OCCURS IN THE GOLGI-COMPLEX OF ISOLATED RAT HEPATOCYTES - EVIDENCE OF PARTIAL RETENTIONIN THE GOLGI

Using weakly basic amines, we investigated the step at which the secre tion kinetics of concanavalin-A-retained and nonretained alpha 1-acid glycoprotein glycoforms diverge in isolated rat hepatocytes. Both chlo roquine and primaquine, whose action on protein secretion is targeted to terminal domains of the Golgi apparatus, cancelled the kinetic diff erence without influencing carbohydrate chain sialylation. To test for a possible interaction of alpha 1-acid glycoprotein with Golgi membra nes, we also permeabilized control and primaquine-treated hepatocytes, as well as purified Golgi preparations, with saponin. In each case, w e found that alpha 1-acid glycoprotein was associated with Golgi membr anes, the association being more marked in primaquine-treated cells th an in control cells. Membrane-bound alpha 1-acid glycoprotein appeared to be preferentially retained on concanavalin A. Such retention could account for the divergent secretion kinetics of alpha 1-acid glycopro tein glycoforms.