Laser-Flash Photoaffinity Labeling of Acetylcholine Receptors with Millisecond Time Resolution

The Helix‐M2 Model of the Ion Channel of the Nicotinic Acetylcholine Receptor

“…It has been shown to not bind to the same sites as acetylcholine, to have only one binding site per AChR (i.e., one per two acetylcholine-binding sites), to compete with phencyclidin [18J and with histrionicotoxin [19J, and to block the cation current through the channel in a voltage-dependent manner [20,21]. A hyperpolarization of the membrane by 30 mV decreased the ID so by about one-fourth of a log unit [21].…”

“…It has been shown to not bind to the same sites as acetylcholine, to have only one binding site per AChR (i.e., one per two acetylcholine-binding sites), to compete with phencyclidin [18J and with histrionicotoxin [19J, and to block the cation current through the channel in a voltage-dependent manner [20,21]. A hyperpolarization of the membrane by 30 mV decreased the ID so by about one-fourth of a log unit [21]. 3H-labeled TPMP+ was used to photolabel the walls of the channel (or the walls of the channel entrance, respectively, see below).The labeled portions of the AChR subunits were identified by i) separation of the labeled subunits, ii) by tryptic and cyanogen bromide cleavage of the purified labeled subunits, iii) and finally, by sequencing the labeled HPLC-purified tryptic (resp.…”