Open AccessRole of glycosylation and protein synthesis in insulin receptor metabolism by 3T3-L1 mouse adipocytes.
Author(s) -
Brent C. Reed,
Gabriele V. Ronnett,
M. Daniel Lane
Publication year - 1981
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.78.5.2908
Subject(s) - cycloheximide , tunicamycin , insulin receptor , receptor , glycosylation , insulin , protein biosynthesis , protein degradation , n linked glycosylation , medicine , biochemistry , glycoprotein , biology , endocrinology , chemistry , insulin resistance , endoplasmic reticulum , unfolded protein response , glycan
The roles of glycosylation and protein synthesis in the maintenance of insulin receptor levels and turnover rates in 3T3-L1 adipocytes were investigated. The heavy isotope density-shift technique was employed to determine the effects of inhibitors of these processes on the rates of synthesis and degradation of cellular insulin receptors. Inhibitors of protein synthesis--i.e., cycloheximide and puromycin--markedly decreased the rate of degradation of the insulin receptor, the half-life for receptor decay increasing from 7.5 hr without to 25 hr with inhibitor. The continued synthesis of a short-lived protein appears to be necessary for normal insulin receptor turnover. Tunicamycin, a potent inhibitor of core oligosaccharide addition in the formation of N-glycosidically linked glycoproteins, caused the depletion of cell-surface and total cellular detergent-extractable insulin receptors. This inhibitor totally prevented the formation of functional newly synthesized insulin receptor, yet receptor degradation was affected minimally. Thus, glycosylation of the receptor appears to be required for its activation after translation.