Early and late functions associated with the Golgi apparatus reside in distinct compartments.
Year: 1981
Type: article
Abstract: Enzymes that catalyze the two successive stages of Golgi-associated processing of asparagine-linked oligosaccharides distributed differently when membranes from Chinese hamster ovary cells were centrifuged in a sucrose density gradient. A mannosidase that removes only outer, alpha-1,2-linked mannose residues from the precursor oligosaccharides of the vesicular stomatitis viral G protein (to yield a "trimmed" oligosaccharide core) was separated from enzymes (galactosyl- and sialyltransferases) that act in the later, terminal stage of glycosylation. Freshly acylated G protein with newly trimmed oligosaccharides banded in the distribution of early-acting membranes, defined by the mannosidase, whereas G protein pulse-labeled with [3H]galactose distributed in the profile of the late-acting membranes. G protein present in the early-acting membranes in crude fractions could be terminally glycosylated by incubation with exogenous Golgi membranes in vitro; G protein lost its ability to be processed in vitro as it appeared to enter the late-acting membranes in vivo. These experiments reveal the existence of two distinct compartments through which intracellularly transported proteins such as G pass in sequence as Golgi-associated processes are carried out. It is likely that these compartments consist of cisternae on the cis and trans sides of the Golgi stack.
Authors: W G Dunphy, E Fries, L J Urbani, J E Rothman
Institution: Stanford University
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
Funder: National Institutes of Health
OpenAlex ID: W2062360693