Functional correlates of low molecular weight peptide synthesis in Aplysia neurons

An attempt was made to determine whether the synthesis of low molecular weight proteins by certain neurons of Aplysia could be correlated with either pacemaker activity or neurosecretion. Electrophysiological tests indicated that the spontaneous generation of action potentials in cells L8 and L9 is due to an endogenous pacemaker mechanism. Gel electrophoresis of proteins synthesized by these neurons showed no evidence of low molecular weight material. The non-neurosecretory interneuron L10 synthesizes a 12,000 dalton protein, whereas the silent neurosecretory cell L5 synthesizes a lower molecular weight peptide. Taken with previous findings, these results indicate that there is no correlation between pacemaker activity and the synthesis of these peptides. There is, however, a strict correlation between neurosecretory activity and the synthesis of proteins of molecular weights lower than 12,000 daltons.