IDENTIFICATION OF LECTIN-LIKE SUBSTANCES RECOGNIZING GALACTOSYL RESIDUES OF GLYCOCONJUGATES ON THE PLASMA-MEMBRANE OF MARROW SINUS ENDOTHELIUM

  • 1 January 1985
    • journal article
    • research article
    • Vol. 65  (5) , 1163-1171
Abstract
Plasma membrane components capable of specific binding to the sugar residues of glycoproteins were recently identified in several cell systems and implicated in the recognition and specific uptake of soluble or membrane-bound glycoproteins. Because the endothelium of [rat] bone marrow sinuses is the site of massive cellular and molecular traffic that is often specific, the surface of sinus endothelium was studied for the presence of sugar-recognizing systems. Neoglycoprotein probes were synthesized by covalently binding bovine serum albumin (BSA) to activated pyrannose form of galactose, fucose, or mannose. The probe was then labeled with colloidal gold. Galactosyl-BSA gold bound to endothelial membrane at 4.degree. C and was internalized at 37.degree. C. Both the binding and the internalization were inhibited in the presence of excess unlabeled galactosyl-BSA. Gold-labeled mannosyl-BSA and fucosyl-BSA did not bind to the endothelium. Nor did BSA-gold without galactosyl residues bind to endothelial membrane, confirming that galactosyl moiety was responsible for the binding. The uptake of galactosyl-BSA was further confirmed by perfusion of 125I-galactosyl-BSA into the abdominal aorta. Small but highly specific uptake was noted in tibias and femurs. These data provide evidence for the presence of a lectin-like substance on the luminal surface of marrow endothelial membrane capable of specific interaction with galactosyl residues of circulating and cell-bound glycoproteins and may provide a mechanisn for specific recognition of these glycoproteins.

This publication has 20 references indexed in Scilit: