Probable ligand of isoforms a and b of the calcitonin receptor-like protein, pdfr-1, a G-protein coupled receptor (PubMed:18390545). May not signal through isoform c of pdfr-1 (PubMed:18390545). Involved in locomotion; more specifically mate searching behavior of males, independent of nutritional status (PubMed:18390545, PubMed:22579613, PubMed:23143519, PubMed:30024377). Involved in regulating the male-specific expression of TGFbeta-like daf-7 in the ASJ chemosensory neurons (PubMed:30024377). Plays a role in circadian rhythms of locomotor activity (PubMed:26113231). Involved in mediating arousal from the sleep-like state called lethargus, which occurs during molting between larval and adult stages, in part by regulating touch sensitivity, and working in concert with neuropeptide flp-2 (PubMed:23764289, PubMed:27585848). In the presence of food, plays a role in initiating and extending exploratory roaming behavior, in opposition to 5-hydroxytryptamine (serotonin) signaling. Expressed throughout postembryonic life (PubMed:19686386). Expressed in hermaphrodites in the interneurons ADAL/R and PVT, the chemosensory neuron pairs ASI, ASK, PHA and PHB, the RMED, RMEV and RID motor neurons, the sensory neuron pair ADE, the PQR mechanosensory neuron and in the PVPL/R interneurons (PubMed:19686386, PubMed:23764289). Also expressed in rectal gland cells rectD and rectVL/R, and the intestino-rectal valve cells virL/R (PubMed:19686386). Expressed in both sexes in the head interneurons SAAV, SAAD, SIAV, AVB, AIM, RMG, and in the tail in the interneurons PVN, LUA, PVT, and the pair PVS and PVU (referred to as PVP left and right in the hermaphrodite) (PubMed:23143519, PubMed:23764289, PubMed:23972393). Expressed in male-specific ventral cord neurons CP7 and CP8, and PDC (PubMed:23143519). Expression from the AIM interneurons in males is involved in mate searching behavior (PubMed:23143519). Conditional knockdown in AVB, PVP, and SIAV neurons reduces exploratory roaming behavior. Extended N-terminus. Extended N-terminus.