PRIMARY STRUCTURE OF THE HUMAN MUSCLE ACETYLCHOLINE-RECEPTOR - CDNA CLONING OF THE GAMMA-SUBUNIT AND EPSILON-SUBUNIT

cDNA sequences encompassing the full coding region for the human muscl e acetylcholine receptor (AChR) epsilon and gamma subunits have been i solated. The deduced amino-acid sequences indicate that the mature eps ilon subunit contains 473 amino acids and is preceded by a 20-amino-ac id signal peptide. As predicted from genomic clones, the gamma subunit contains 495 amino acids preceded by a 22-amino-acid signal peptide. In common with the human alpha, beta, gamma and delta subunits the eps ilon subunit is highly conserved between mammalian species. The epsilo n subunit gene is not closely linked to the gamma and delta subunits o n chromosome 2 but rather is located with the beta subunit on chromoso me 17. Expression of the alpha-, beta-, gamma-, delta- and epsilon-sub unit cRNAs in rabbit-reticulocyte lysates followed by analysis on SDS/ PAGE show glycosylated proteins with apparent molecular masses of 44-6 0 kDa.