PT - JOURNAL ARTICLE AU - Connie R. Jiménez AU - Sabine Spijker AU - Simone de Schipper AU - Johannes C. Lodder AU - Cornelis Kees Janse AU - Wijnand P. M. Geraerts AU - Jan van Minnen AU - Naweed I. Syed AU - Alma L. Burlingame AU - August B. Smit AU - KaWan Li TI - Peptidomics of a Single Identified Neuron Reveals Diversity of Multiple Neuropeptides with Convergent Actions on Cellular Excitability AID - 10.1523/JNEUROSCI.2566-05.2006 DP - 2006 Jan 11 TA - The Journal of Neuroscience PG - 518--529 VI - 26 IP - 2 4099 - http://www.jneurosci.org/content/26/2/518.short 4100 - http://www.jneurosci.org/content/26/2/518.full SO - J. Neurosci.2006 Jan 11; 26 AB - In contrast to classical transmitters, the detailed structures and cellular and synaptic actions of neuropeptides are less well described. Peptide mass profiling of single identified neurons of the mollusc Lymnaea stagnalis indicated the presence of 17 abundant neuropeptides in the cardiorespiratory neuron, visceral dorsal 1 (VD1), and a subset of 14 peptides in its electrically coupled counterpart, right parietal dorsal 2. Altogether, based on this and previous work, we showed that the high number of peptides arises from the expression and processing of four distinct peptide precursor proteins, including a novel one. Second, we established a variety of posttranslational modifications of the generated peptides, including phosphorylation, disulphide linkage, glycosylation, hydroxylation, N-terminal pyroglutamylation, and C-terminal amidation. Specific synapses between VD1 and its muscle targets were formed, and their synaptic physiology was investigated. Whole-cell voltage-clamp analysis of dissociated heart muscle cells revealed, as tested for a selection of representative family members and their modifications, that the peptides of VD1 exhibit convergent activation of a high-voltage-activated Ca current. Moreover, the differentially glycosylated and hydroxylated α2 peptides were more potent than the unmodified α2 peptide in enhancing these currents. Together, this study is the first to demonstrate that single neurons exhibit such a complex pattern of peptide gene expression, precursor processing, and differential peptide modifications along with a remarkable degree of convergence of neuromodulatory actions. This study thus underscores the importance of a detailed mass spectrometric analysis of neuronal peptide content and peptide modifications related to neuromodulatory function.