ABSTRACT A monoclonal antibody that recognizes a cell-surface glycoprotein associated with glucose transport was reported previously. Additional information about the function and intracellular distribution of the antigen recognized by this antibody is presented. The monoclonal antibody recognizes a cell-surface and a cytoplasmic determinant. The density of the cell-surface determinant is heterogeneous within the cell population. The subpopulation of cells that carry the cell-surface determinant at high density correspond with a subset of cells that incorporate 2-deoxy-D-[3H]glucose more rapidly than the population as a whole. The monoclonal antibody is used, with cell-affinity chromatography, to isolate this subset of cells. The cytoplasmic determinant, to which the antibody binds, is associated with the cytoplasmic microfilaments but the antibody is not absorbed by actin. The cell-surface and cytoplasmic components are not identical since the apparent affinity of the antibody for each site is different. The portion of the antigen in the membrane behaves as an integral membrane protein while the remainder is tightly associated with the detergent-insoluble cytoskeleton. The expression of the antigen on the cell surface is modified by covalent attachment of an inhibitor of anion transport, 4,4’-diisothiocyano-2,2’-disulphonic stilbene. The possible interaction of the anion/lactate transporter with the glucose transporter is discussed.