The CHRNA4 gene is more than 17 kb long and contains 6 exons spanning a total of 5,486 bp. The mRNA is 1884 bp, encoding a protein of 627 amino acids. The largest exon among the 6 coding exons is exon 5, which is 1375 bp. As with other nAChR subunits, the polypeptide chain of α4 has a large extracellular N-terminal domain, which is glycosylated. It contains 4 transmembrane domains; a large cytoplasmic loop is between the third and fourth transmembrane domains. A short C-terminal domain is extracellular. According to Uniprot, there are 270 amino acids in the cytoplasmic loop, and exon 5 codes the first 256 of these amino acids.
