Protein Glycosylation in Mammalian Cells

Abstract

The principal organelles in mammalian cells where protein glycosylation occurs are the endoplasmic reticulum and Golgi apparatus (Kornfeld and Kornfeld 1985). Among the glycosylation reactions occurring in the endoplasmic reticulum are the initiation of N-glycosylation of proteins and the incorporation of mannose and glucosamine into the glycosylphosphatidylinositol anchor of proteins (Kornfeld and Kornfeld 1985; Doering et al. 1990). Following these reactions, proteins move via vesicles to the Golgi apparatus where N-linked glycoproteins undergo processing and further glycosylation and where also O-glycosylation reactions occur (Kornfeld and Kornfeld 1985; Pfeffer and Rothman 1987; Hirschberg and Snider 1987; Abeijon and Hirschberg 1987). We will briefly summarize in this review the current important features regarding the above glycosylation reactions, among them topographical issues as well as the cloning of some of the enzymes catalyzing the above reactions.