STRUCTURE AND REGULATION OF EXPRESSION OF THE ACETYLCHOLINESTERASE GENE

Acetylcholinesterase, an enzyme essential for the termination of the a ction of acetylcholine, is encoded by a single gene. Alternative mRNA processing gives rise to the expression of enzyme forms with three dis tinct carboxyl-termini. These structural differences govern the cellul ar disposition of the expressed enzyme but do not influence catalytic activity. Alternative polyadenylation signals give rise to distinct 3' non-coding regions which are likely to affect mRNA stability. Alterna tive splicing also occurs at the 5' end of the gene where two promoter regions can be identified. Hence, regulation of expression of the gen e occurs at 3 levels, transcriptional through alternative promoters, t ranslational by affecting mRNA stability and processing of distinct mR NAs and post-translationally by giving rise to distinct peptide chains which are processed differently. Recombinant DNA studies have also be en extended to modifying protein structure through site-specific mutag enesis and studying the function of the mutant enzymes.