Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors.
The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.
Kozarsky
K F
KF
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Call
S M
SM
Dower
S K
SK
Krieger
M
M
D000818:Animals; D002460:Cell Line; D005434:Flow Cytometry; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D006031:Glycosylation; D007376:Interleukin-2 / Q000378:metabolism; D009154:Mutation; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis / Q000235:genetics*
D006023:Glycoproteins; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2