The Iodination and Turnover of Macrophage Plasma Membrane Polypeptides

Abstract

The functional properties of the macrophage cell surface have been characterized extensively. In contrast, there are few data on the biochemistry and molecular organization of macrophage plasma membrane. A major obstacle is the lack of satisfactory methods for isolating pure membrane fractions from these cells. To circumvent the difficulties of physical separation, we explored the use of non-permeant, membrane-specific labels to identify membrane proteins on macrophages. We adapted the lactoperoxidase-glucose oxidase catalyzed iodination method of Hubard & Cohn (1972, 1975a) atthe label plasma membrane of mouse peritoneal macrophages and study their physical and physiological properties. tiWe have attempted 1) atto define the optimal conditions for labelling macrophage cell surface; 2) to characterize labelled membrane proteins of resident macrophages and macrophages generated during inflammatory response; and 3) to examine the kinetics of turnover of labelled proteins.