Release of sialyltransferases from rat liver Golgi membranes by a cathepsin D-like proteinase: comparison of the release of Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase, Gal beta 1-3(4)GlcNAc alpha 2-3 sialyltransferase and lactosylceramide alpha 2-3 sialyltransferase (SAT-1).
The activities of Gal beta 1-3(4)GlcNAc alpha 2-3 sialyltransferase and SAT-1 were measured in rat liver Golgi in inflammation; both enzymes decreased by about 50%. This compares with increases of about 3-fold for the Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase. All three sialyltransferases were released from disrupted Golgi membranes by incubation at reduced pH which activates an endogenous cathepsin D which is believed to be the lysosomal enzyme. Pepstatin A was found to block the release of all three sialyltransferases providing support for the role of cathepsin D as the proteinase that clips the catalytic portions of the enzymes from their membrane anchor and stem regions.
Richardson
K
K
Department of Chemistry, University of Manitoba, Winnipeg, Canada.
Jamieson
J C
JC
D000818:Animals; D002240:Carbohydrate Sequence; D002402:Cathepsin D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D056486:Chemical and Drug Induced Liver Injury / Q000201:enzymology; D006056:Golgi Apparatus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000201:enzymology; D008969:Molecular Sequence Data; D010436:Pepstatins / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D051381:Rats; D012799:Sialyltransferases / Q000378:metabolism*; D014425:Turpentine / Q000633:toxicity; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
D010436:Pepstatins; C014195:Streptomyces pepsin inhibitor; D012799:Sialyltransferases; C021343:haematoside synthetase; D002402:Cathepsin D; C031375:pepstatin; D014425:Turpentine; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase