A cDNA clone encoding neuropeptides isolated from Aplysia neuron L11

Single nerve cells can use more than one substance as extracellular chemical messengers. Classical transmitters have been shown to coexist in the same neuron and possibly even in the same vesicle as neuroactive peptides. Furthermore, multiple neuroactive peptides, which are thought to be coreleased, are often encoded in the same precursor assuring stoichiometric synthesis. The precise organization of multiple message systems and the physiological significance of the coexistence is poorly understood. The abdominal ganglion of the gastropod mollusc Aplysia contains a number of identified neurons that are cotransmitter candidates. One such cell, L11, is cholinergic and probably also uses biologically active peptides. Differential screening with labeled cDNA was used to isolate cDNA clones expressed specifically in the bag cells and abdominal ganglion neurons L11 or R15. Analysis of an L11-specific clone suggests that it encodes a 14.7-kDa protein that is the precursor for the secreted peptides. The poly(A)⁺ RNA transcript is ~1.2 kilobases and there are 1-3 copies of this gene in the Aplysia haploid genome.