Fig. 2.

MALDI-TOF-MS analysis of the right parietal neurons containing heptapeptides (HP neurons). a Predicted protein precursor encoded by mRNA2 (the splicing product of the primary transcript of the FMRFamide gene) showing the putative neuropeptides contained within the precursor. Note that we assumed that the DEILSR containing 35 amino acid peptide (acidic peptide) is not cleaved into two smaller peptides. b Mass spectrum of a single retrograde-stained parietal heptapeptide-containing neuron. Note that all the ion species with molecular mass corresponding to those of predicted peptides from the FLRF precursor were detected: GDPFLRFamide, 850.40 Da; SDPFLRFamide, 880.41 Da; SDPYLRFamide, 896.40 Da; pQHYMRFamide, 863.34 Da; SKPYMRFamide, 927.42 Da and GPSRSSFPRYamide, 1152.51 Da. Unlabeled peaks correspond to unknown neuropeptides (Novel) that need to be further chemically characterized. All mass values quoted are for the [M + H] ion. Percent intensity refers to the relative signal intensity. The most intense peak (base peak) corresponds to GDPFLRFamide and is represented as 100 %. All other peaks are, therefore, represented as a proportion of the base peak intensity. The counts on the right-hand vertical axis show the absolute intensity