The function of NPS (neuropeptide S, Ensembl gene identifier ENSG00000214285) is as follows. Ligand for NPSR1 (PubMed:15312648, PubMed:15947423, PubMed:16720571, PubMed:16790440). Binds to its receptor with nanomolar affinity and initiates a G(q)/GNAQ-dependent phospholipase C-activating signaling pathway. This results in Ca(2+) mobilization from intracellular stores and increased intracellular Ca(2+) levels (PubMed:15312648, PubMed:15947423, PubMed:16720571, PubMed:16790440, PubMed:25714705, PubMed:26865629). In addition to this pathway, NPS binding to its receptor activates cAMP/PKA signal transduction (PubMed:26865629). Finally, both pathways converge to activate ERK1/ERK2 phosphorylation and signaling cascade (PubMed:26865629). Modulates arousal and anxiety. May play an important anorexigenic role (By similarity). {ECO:0000250|UniProtKB:P0C0P8, ECO:0000269|PubMed:15312648, ECO:0000269|PubMed:15947423, ECO:0000269|PubMed:16720571, ECO:0000269|PubMed:16790440, ECO:0000269|PubMed:25714705, ECO:0000269|PubMed:26865629}.