Genomic and phenotypic expression of autonomic neurons

We found that catecholamine biosynthetic enzymes, tyrosine hydroxylase, dopamine B-hydroxylase and phenylethanolamine N-methyl-transferase share similar protein domains in their primary structures, and therefore are coded for by a single gene or a family of genes. In a recent report, we also demonstrated that antisera directed against tyrosine hydroxylase, choline acetyltransferase and glutamate decarboxylase cause specific complement-mediated lysis of dopaminergic, cholinergic and GABA-ergic subpopulation of synaptosomes, respectively. This implies that the neurotransmitter biosynthetic enzyme and the specific nerve ending protein(s) also share similar protein domain(s). Therefore, we postulate that the specific neurotransmitter biosynthetic enzyme and a certain membrane protein of the nerve endings probably share similar gene coding sequences and that coordinate expression of these proteins may determine the phenotype of the neuron.