Translocation of uridine diphosphate N-acetylgalactosamine into vesicles derived from rat liver golgi apparatus

Conference · Thu May 01 00:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6986148

Abeijon, C; Hirschberg, C B

N-acetylgalactosamine is the first sugar attached to the peptide backbone of many O-linked glycoproteins. A precursor in the biosynthesis of these macromolecules is UDP-GalNAc, which is synthesized in the cytosol. The mechanism by which this sugar nucleotide becomes available to the specific transferases in the lumen of the Golgi apparatus (GA) is not known. Incubation of sealed, right side out vesicles derived from rat liver GA with UDP-(/sup 3/H)GalNAc resulted in a 100-fold accumulation of soluble radioactive species within these vesicles compared to the incubation medium. Translocation of UDP-GalNAc into the lumen of GA vesicles was temperature dependent and saturable with an apparent Km of 4 ..mu..M. The specific translocation rate of UDP-GalNAc into vesicles from the GA was 5 to 10-fold higher than into vesicles derived from the rough endoplasmic reticulum (RER). The specific activity of N-acetylgalactosaminyltransferase (using apomucin as an exogenous acceptor) was 50-fold higher in membranes derived from the GA than those derived from the RER. These results strongly suggest that in rat liver the addition of GalNAc to the peptide backbone occurs in the lumen of the GA.

• Research Organization: St. Louis Univ., MO
• OSTI ID: 6986148
• Report Number(s): CONF-8606151-; TRN: 86-039029
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
OLIGOSACCHARIDES
MEMBRANE TRANSPORT
TRANSFERASES
ENZYME ACTIVITY
CELL MEMBRANES
LIVER
PEPTIDES
RATS
TRACER TECHNIQUES
TRANSLOCATION
TRITIUM COMPOUNDS
ANIMALS
BODY
CARBOHYDRATES
CELL CONSTITUENTS
DIGESTIVE SYSTEM
ENZYMES
GLANDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RODENTS
SACCHARIDES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques