Clearance of circulating gamma-glutamyltransferase by the hepatic galactose receptor. Variability in clearance rate due to carbohydrate heterogeneity of the enzyme.
The clearance and organ uptake of gamma-glutamyltransferase was studied by injecting the purified human liver enzyme intravenously in the rat. The enzyme was almost exclusively taken up by liver hepatocytes with a rapid initial uptake. The clearance was significantly inhibited by asialofetuin as well as by galactose and fucose. The uptake of neuraminidase-treated enzyme was much more rapid than that of the native enzyme. Subfractions of gamma-glutamyltransferase obtained by lectin affinity chromatography revealed significant differences in clearance rates. The data strongly indicates that the uptake of circulating gamma-glutamyltransferase involves the galactose (asialo-glycoprotein) receptor of the parenchymal cells, and that the heterogeneity of gamma-glutamyltransferase results in varying clearance rates.
Huseby
N E
NE
Institute of Medical Biology, University of Tromsø, Norway.
Mortensen
B
B
Smedsrød
B
B
D000818:Animals; D050260:Carbohydrate Metabolism; D002478:Cells, Cultured; D005690:Galactose / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000378:metabolism*; D005723:gamma-Glutamyltransferase / Q000737:chemistry / Q000378:metabolism*
D011956:Receptors, Cell Surface; C039707:galactose receptor; D005723:gamma-Glutamyltransferase; D005690:Galactose