The mongoose acetylcholine receptor α-subunit: Analysis of glycosylation and α-bungarotoxin binding

The mongoose AChR α-subunit has been cloned and shown to be highly homologous to other AChR α-subunits, with only six differences in amino acid residues at positions that are conserved in animal species that bind a- bungarotoxin (α-BTX). Four of these six substitutions cluster in the ligand binding site, and one of them, Asn-187, forms a consensus N-glycosylation site. The mongoose glycosylated α-subunit has a higher apparent molecular mass than that of the rat glycosylated α-subunit, probably resulting from the additional glycosylation at Asn-187 of the mongoose subunit. The in vitro translated mongoose α- subunit, in a glycosylated or non-glycosylated form, does not bind α-BTX, indicating that lack of α-BTX binding can be achieved also in the absence of glycosylation.