Major bovine brain stem glycoproteins sugar-specifically recognized by endogenous 14 kDa galactose-binding lectin

Abstract

In order to identify the complementary glycoproteins (receptors) that are recognized in bovine brain stem by endogenous 14 kDa galactose-binding lectin (BBL), probable glycoproteins were first selected by affinity chromatography of soluble tissue glycoproteins on Rinicus communis agglutinin (RCA)-Sepharose since this lectin had similar sugar specificity to the endogenous lectin. From Western blot of RCA-binding glycoproteins, the lectin, as its peroxidase conjugate sugar-specifically recognized chiefly an 84 kDa glycoprotein subunit and a few minor subunits. On alkaline pH PAGE of the RCA-binding brain stem glycoproteins, a prominent fast moving protein was separated which, on electroelution and dot blotting, was also recognized by BBL sugar-specifically. This glycoprotein was composed of 55 kDa and 58 kDa subunits as seen by SDS-PAGE and was also immunologically distinct from the 84 kDa subunit. Qualitative test on dot blots of the electroeluted glycoproteins using peroxidase conjugates of plant lectins of varying specificities as well as the human serum anti-alpha-galactoside antibody indicated differences in carbohydrate composition between the 84 kDa subunit and the alkaline PAGE fast moving glycoprotein. Membrane-bound brain stem glycoproteins were not recognized by BBL.