Journal of Neuroscience, Vol 7, 854-863, Copyright © 1987 by Society for Neuroscience
Proteolytic processing of the Aplysia egg-laying hormone and R3-14 neuropeptide precursors
R Newcomb and RH Scheller
A number of animal behaviors are influenced by the actions of neuropeptides
that arise from the processing of complex protein precursors. In this
report we investigate the proteolytic processing of neuropeptide precursors
expressed in the Aplysia californica bag cells, which govern egg-laying,
and neurons R3-14, which mediate aspects of cardiac output. Peptides were
purified by fractionation on 2 high- pressure liquid chromatography systems
followed by determination of amino acid compositions. Most of these
compositions are indicative of processing products derived from the
egg-laying hormone (ELH) and R3-14 precursors by cleavage at basic
residues. We characterized 9 peptides that arise from the ELH precursor by
cleavage of the signal sequence, as well as 7 out of 8 dibasic residues and
at least 1 single Arg residue. The peptides range in size from 5 to about
60 amino acids. The R3-14 neuropeptide precursor is cleaved at 2 internal
dibasic residues in addition to the signal sequence, resulting in 3
peptides. Shortened forms of several peptides probably result from amino-
and carboxy- terminal peptidase action. It is likely that the complex
mixtures of neuropeptides arising from these single protein precursors are
co- secreted.
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