Enzymatic deglycosylation of the dendrotoxin‐binding protein

Abstract

The neuronal membrane protein which binds the K+-channel ligands dendrotoxin, mast cell degranulating peptide, and β-bungarotoxin was purified from rat brain membranes. When analysed on 10% SDS gel electrophoresis, the purified protein contained two peptides: the toxin-binding subunit of apparent Mr, 90 000 and another peptide of Mr, 38 000. Neuraminidase treatment reduced the Mr, of the toxin-binding subunit to 70 000. Glycopeptidase F gave a further reduction to Mr, 65 000. In contrast, the peptide of Mr, 38 000 showed no change in Mr, upon treatment with neuraminidase and/or glycopeptidase F. It is concluded that the toxin-binding subunit of the dendrotoxin-binding protein, a presumptive K+ channel, is a sialated membrane protein with a peptide core of, at most, Mr, 65 000