Peptides

More than 50 small peptides are thought to be neurotransmitters. A few are also hormones or neuroendocrines. They can be assembled into families on the basis of:

- Similarities in their amino acid series.

- Being derived by cleavage of a general large predecessor polypeptide encoded by a single mRNA molecule. Frequently the peptides created from a general polypeptide have associated functions. Different cells might process the similar precursor or it’s mRNA in various ways. For illustration, various peptides are made from pro-opiomelanocortin by hypothalamic neurons and endocrine cells in the forward pituitary.