Glycoprotein metabolism in rat colonic epithelial cell populations with different proliferative activities.

Epithelial cells with different proliferative activities were isolated from rat proximal and distal colon. The distribution of fucose, hexose, hexosamine, and sialic acid as well as the activities of three glycosyltransferases, eight glycosidases, and a nucleotide sugar pyrophosphatase, enzymes involved in glycoprotein metabolism, were then examined in these cells. The results of the present study demonstrate that: (1) all proximal cell populations appear to possess a higher content of hexose, fucose, and sialic acid than their distal counterparts; (2) in general, the proximal colonic populations have higher glycosyltransferase but similar glycosidase activities than their distal counterparts; (3) proliferative cells in both colonic regions have greater glycosyltransferase and glycosidase activities than non-proliferative cells, although their carbohydrate content is similar. These findings suggest that alterations in glycoprotein metabolism exist during differentiation along the length of the rat colon. Furthermore, these data indicate that certain enzymes involved in glycoprotein metabolism may serve as markers for cellular differentiation in this organ.