Alpha 3, alpha 5, and beta 4: three members of the rat neuronal nicotinic acetylcholine receptor-related gene family form a gene cluster.
We have identified two additional members of the neuronal nicotinic acetylcholine receptor (nAChR)-related gene family. cDNA clones for one new gene, designated alpha 5, were isolated from rat hippocampus and rat PC12 cell line cDNA libraries. The alpha 5 gene encodes a protein of 48,800 daltons (424 amino acids) which exhibits significant overall amino acid sequence identity with the previously cloned rat nAChR subunits alpha 1 (49%), alpha 2 (55%), alpha 3 (52%), and alpha 4 (49%). Features characteristic of other nAChR alpha-subunits are present such as conserved cysteine residues at positions 127, 141, 191, and 192, and four strongly hydrophobic domains. A second addition to the nAChR-related gene family, designated beta 4, is encoded in overlapping rat genomic clones lambda DD15 and lambda RG518A. The beta 4 gene, encoding a mature protein of 53,300 daltons (475 amino acids), consists of 6 exons and has a transcription unit length of approximately 18 kilobase pairs. The beta 4 gene encoded protein shows considerable amino acid sequence identity with nAChR beta 1 (43%), beta 2 (64%), and beta 3 (44%) subunits. Northern blots showed that, along with alpha 3 and beta 2, transcripts for both the alpha 5 and beta 4 genes are present in the PC12 cell line, while in situ hybridization experiments demonstrated expression of the alpha 5 and beta 4 genes in a small number of nuclei in the central nervous system. Finally, the genes that encode the beta 4, alpha 3, and alpha 5 proteins are transcribed with convergent polarities and form a tightly linked gene cluster spanning approximately 60 kilobase pairs.
Molecular Neurobiology Laboratory, Salk Institute, San Diego, California 92138.
J
J
Boulter
A
A
O'Shea-Greenfield
R M
RM
Duvoisin
J G
JG
Connolly
E
E
Wada
A
A
Jensen
P D
PD
Gardner
M
M
Ballivet
E S
ES
Deneris
D
D
McKinnon
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D015870:Gene Expression; D006624:Hippocampus / Q000032:analysis; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D005810:Multigene Family; D009474:Neurons / Q000032:analysis*; D009693:Nucleic Acid Hybridization; D010673:Pheochromocytoma; D012313:RNA / Q000032:analysis; D051381:Rats; D011978:Receptors, Nicotinic / Q000235:genetics*; D015183:Restriction Mapping; D014018:Tissue Distribution; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D046911:Macromolecular Substances; D011978:Receptors, Nicotinic; D012313:RNA; D004247:DNA