Molecular cloning of human neuronal nicotinic receptor alpha 3-subunit

Neuronal nicotinic receptors (nAchRs) have been isolated or cloned in insect, bird and mammalian neurons, but no information exists on the primary structure of human neuronal nAchRs. By screening a cDNA library from the human neuroblastoma cell line IMR 32 with a cDNA probe corresponding to the full length of rat alpha 3-nicotinic subunit, we have identified an open reading frame encoding a protein of 502 amino acids. This protein shows all the features of members of the ligand-gated receptor superfamily and has two cysteine residues at positions 192, 193 which are typical of the nicotinic alpha-subunits. Because of its high homology to rat alpha 3 (93% amino acid identity), we conclude that we have cloned the human alpha 3-nicotinic subunit.