The M2 delta transmembrane domain of the nicotinic cholinergic receptor forms ion channels in human erythrocyte membranes.

A synthetic peptide with the sequence of the M2 delta segment of the nicotinic acetylcholine receptor from Torpedo californica forms pores in human erythrocyte membranes as determined by hemoglobin and potassium release. This peptide forms a permeability pathway with an apparent cross-sectional diameter of 7-9 A. The M2 delta pore is oligomeric and a pentamer is the species that accounts for the properties of the permeation path. Peptides that mimic other identifiable segments of the Torpedo acetylcholine receptor, M1 delta and MIR, do not form channels in erythrocytes under the same conditions.