G-protein coupled receptor that antagonizes the negative effects of the gcy-35 oxygen sensor on spermatogenesis (PubMed:28662030). This leads to the maintenance of mitochondrial function in developing spermatocytes and/or spermatids prior to testis maturation during the early larval stages (PubMed:28662030). Regulates the navigational capacity of sperm during hyperoxic conditions ensuring the proper targeting of sperm derived from males to the fertilization site in the uterus of hermaphrodites (PubMed:28662030). May act in the same signaling pathway as the neuropeptide flp-21 (PubMed:28662030). Detected in ciliated sensory neurons. Expressed in the head sensory neurons ASI, ASK and AWB (PubMed:28662030). Not expressed in male somatic gonads or sperm (PubMed:28662030). Expressed throughout larval development and adulthood. Reduced brood size, which is in part due to an abnormal distribution of male-derived sperm in the hermaphrodite uterus following mating, with sperm reversing course frequently and accumulating at the spermathecal-uterine valve 1 hour following mating (PubMed:28662030). No visible defects in oogenesis (PubMed:28662030). Double knockout with the mcu-1 ju1154 mutant suppresses the sperm navigation defect in the srb-13 single mutant (PubMed:28662030). Belongs to the nematode receptor-like protein srb family.