F. Vicenteagullo et al., ACETYLCHOLINE-RECEPTOR SUBUNIT HOMOMER FORMATION REQUIRES COMPATIBILITY BETWEEN AMINO-ACID-RESIDUES OF THE M1 AND M2 TRANSMEMBRANE SEGMENTS, FEBS letters, 399(1-2), 1996, pp. 83-86
The neuronal nicotinic acetylcholine receptor (nAChR) subunits alpha 3
and alpha 7 have different assembly behavior when expressed in hetero
logous expression systems: alpha 3 subunits require other subunits to
assemble functional nAChRs, whereas alpha 7 subunits can produce homom
eric nAChRs. A previous analysis of alpha 7/alpha 3 chimeric construct
s identified a domain comprising the first putative membrane-spanning
segment, M1, as essential to homomeric assembly. The present study dis
sected further this domain, identifying three amino acid residues, whi
ch are located at the most intracellular third of the M1 transmembrane
segment, as important in the assembly of homomers. Moreover, formatio
n of homooligomeric complexes seems to require a compatible accommodat
ion between this region and certain residues of the second transmembra
ne segment, M2. Thus, compatibility between defined domains of the M1
and M2 transmembrane segments appears as a determinant factor governin
g homomer association of nAChR subunits.