Formation of mannosyl-lipids by an ectomannosyltransferase in suspensions of BALB/c fibroblasts.

A mannosyltransferase has been detected in suspensions of BALB/c fibroblasts incubated with GDP-[14C] mannose. The experimental evidence indicates the cell surface as the most likely site for the enzyme. The transferase synthesizes both glycolipids and glycoproteins. The lipid compounds have properties suggestive of lipid-linked mono- and oligosaccharides which can function as intermediates in glycoprotein synthesis. The formation of these compounds by a cell surface enzyme suggests that lipid-linked intermediates may play an important role in the glycosylation of membrane components.