Introduction

Various transcriptomics and peptidomics approaches have led to the discovery of potential novel peptides and peptide-encoding precursors. Purification of peptides based on a particular bioassay has also led to the identification of bioactive peptide fragments. These include anti-diuretic factor (ADF), NPLP2, NPLP3, NPLP4, ITG-containing, NVP-containing, IDL-containing peptides and various others (Hummon et al., 2006; Hauser et al., 2010; Boerjan et al., 2010; Veenstra 2014; Li et al., 2008). It is still unclear if these represent typical neuropeptides in that they are 1) produced in the nervous system 2) encoded by a larger precursor which contains a signal peptide 3) mediate their effects by activating a GPCR (or other receptor types) and 4) the mature peptide (not just the precursor) has high sequence similarity with its orthologs in other insects. Consequently, several studies have questioned their classification as neuropeptides. Thus, until additional information becomes available supporting their classification as neuropeptides, these peptides should be classified as “potential neuropeptides.”
Precursors encoding NVP and ITG-containing peptides have been identified in the honey bee Apis mellifera (Hummon et al., 2006; Boerjan et al., 2010), the silk moth Bombyx mori (Roller et al., 2008), the red flour beetle Tribolium castaneum (Li et al., 2008), and Locusta migratoria (Veenstra 2014). These peptides have not been properly identified in nervous tissue and no biological activities have been assigned. Thus, it is not yet clear whether they represent bona fide neuropeptides.

Apis-ITG: ITGQGNRIF
Apis-NVP: NVPIYQEPRF

Location

Information not available

Function

Information not available

References

• Boerjan, B., Cardoen, D., Bogaerts, A., Landuyt, B., Schoofs, L., and Verleyen, P. (2010). Mass spectrometric profiling of (neuro)-peptides in the worker honeybee, Apis mellifera. Neuropharmacology 58(1), 248-258. doi: 10.1016/j.neuropharm.2009.06.026.
• Hauser, F., Neupert, S., Williamson, M., Predel, R., Tanaka, Y., and Grimmelikhuijzen, C.J. (2010). Genomics and peptidomics of neuropeptides and protein hormones present in the parasitic wasp Nasonia vitripennis. Journal of proteome research 9(10), 5296-5310. doi: 10.1021/pr100570j.
• Hummon, A.B., Richmond, T.A., Verleyen, P., Baggerman, G., Huybrechts, J., Ewing, M.A., et al. (2006). From the genome to the proteome: uncovering peptides in the Apis brain. Science 314(5799), 647-649. doi: 10.1126/science.1124128. Li, B., Predel, R., Neupert, S., Hauser, F., Tanaka, Y., Cazzamali, G., et al. (2008). Genomics, transcriptomics, and peptidomics of neuropeptides and protein hormones in the red flour beetle Tribolium castaneum. Genome Res 18(1), 113-122. doi: gr.6714008 [pii]10.1101/gr.6714008.
• Roller, L., Yamanaka, N., Watanabe, K., Daubnerova, I., Zitnan, D., Kataoka, H., et al. (2008). The unique evolution of neuropeptide genes in the silkworm Bombyx mori. Insect Biochem Mol Biol 38(12), 1147-1157.
• Veenstra, J.A. (2014). The contribution of the genomes of a termite and a locust to our understanding of insect neuropeptides and neurohormones. Frontiers in Physiology 5. doi: ARTN 454 10.3389/fphys.2014.00454.