[The demonstration of an extramembranous location for the putative amphipathic helix of the acetylcholine receptor].

It has been demonstrated that the lysyl residues at the centers of the potential amphipathic helices of the alpha- and beta-subunits could be readily labeled in native acetylcholine receptor with anionic electrophiles. This result indicates that the regions in the sequences of the alpha- and beta-polypeptides which patterns of hydropathy are those of amphipathic helices are fully exposed on the surface of the native protein and do not span the membrane.