Myelin basic protein binds GTP at a single site in the N-terminus

Myelin basic protein from normal human brain was ADP-ribosylated with Cholera toxin, but not with Pertussis toxin. It bound azido-GTP at a single site in the N-terminal tetrapeptide at the Gln residue. The binding was considerably reduced when GppNHp was present during azido-GTP binding and totally inhibited when GTP gamma S was present. The relevance of this specific binding is not understood at this time.