| Popis: |
Systematic analysis of the α-subunit of the nicotinic acetylcholine receptor (AChR) has led to the identification of the cholinergic binding site. By probing protein blots of proteolysed α-subunits with: α-bungarotoxin (BTX), lectins, sequence-specific antibodies and biotinylated SH reagents, the disulfide arrangement of this subunit has been determined (Mosckovitz and Gershoni 1988) and the a-neurotoxin binding domain has been mapped to the region of a 180–200 (Criado et al. 1986, Neumann et al. 1985; 1986, Pedersen et al. 1986, Wilson et al. 1984; 1985). Indeed, synthetic polypeptides corresponding to this area specifically and directly bind BTX (Gotti et al. 1987; 1988, Mulac-Jericevic and Atassi 1986, Neumann et al. 1986, Ralston et al. 1987, Wilson et al. 1985) as do similar recombinant fusion proteins (Aronheim et al. 1988, Barkas et al. 1987, Gershoni 1987). Moreover, competition assays reveal that these sites bind d-tubocurarine as well. Recently, selective T1 NMR relaxation measurements have shown that the sequence α 184–200 can bind both nicotine and acetylcholine specifically, proving that this region is an essential element of the cholinergic binding site (Fraenkel et al. 1988). |
