J. Biol. Chem., Vol. 255, Issue 9, 3830-3831, 05, 1980
Effects of receptor-specific antibody on the uptake of desialylated glycoproteins in the isolated perfused rat liver
RJ Stockert, U Gartner, AG Morell and AW Wolkoff
Removal of the terminal sialic acid residues from most mammalian
glycoproteins results in their rapid transfer from the circulation into the
liver. In vitro, these desialylated glycoproteins bind to a specific
membrane-associated hepatic lectin which has a ubiquitous distribution
within the liver cell. In the present study, infusion of a specific
antibody to the purified lectin into the portal vein of an isolated
perfused rat liver prior to injection of radiolabeled asialoorosomucoid or
bilirubin reduced the rate of influx of asialoorosomucoid into the liver by
over 80%, while the influx of bilirubin was unchanged. Although uptake of
asialoorosomucoid remained blocked for at least 90 min after excess
antibody was removed from the perfusion system, the total hepatic content
of functional binding protein was nearly normal. These results indicate
that interaction with specific cell surface lectin is essential for removal
of asialoorosomucoid from the circulation. During the 90 min following
infusion of antibody, no functional lectin is restored to the surface of
hepatocytes.
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