Glycosylation and secretion of lipoprotein lipase by 3T3-L1 adipocytes: effects of brefeldin A.
Time courses of synthesis and secretion of lipoprotein lipase (LPL) were examined in 3T3-L1 adipocytes. LPL was glycosylated in the endoplasmic reticulum (ER) within 10 min after synthesis, and was transported after 20-30 min to the trans Golgi where it was converted to the mature form with M(r) = 55,000-58,000, which was resistant to endoglycosidase H (endo H). LPL subunits with M(r) = 55,000-58,000 appeared in the medium within 30 min after synthesis. The effects of brefeldin A (BFA), which inhibits transport of glycoproteins in various types of cells, on secretion and glycosylation of LPL were also examined. BFA completely blocked release of LPL activity into the medium, causing accumulation of the activity in cells. The suppressive effect of BFA on release of LPL activity was reversible. BFA-treated cells synthesized LPL with M(r) = 53,000-55,000 consisting of 2 types of subunits, the main type being totally endo H-sensitive and the other partially endo H-sensitive. No LPL were secreted into the medium by BFA-treated cells.
Masuno
H
H
Department of Medical Laboratory Technology, Ehime College of Health Science, Japan.
Okuda
H
H
D017667:Adipocytes / Q000201:enzymology*; D000818:Animals; D020126:Brefeldin A; D002460:Cell Line; D003517:Cyclopentanes / Q000494:pharmacology*; D006031:Glycosylation; D008071:Lipoprotein Lipase / Q000378:metabolism*; D051379:Mice; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*
D003517:Cyclopentanes; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D008071:Lipoprotein Lipase