TGFBR3L (transforming growth factor beta receptor 3 like) is a gonadotrope-specific inhibin B coreceptor that regulates follicle-stimulating hormone (FSH) synthesis and female fertility. 1 The protein localizes to the plasma membrane of pituitary gonadotrope cells, where it functions alongside betaglycan (TGFBR3) to mediate inhibin B suppression of FSH production. 2 Unlike betaglycan, TGFBR3L exhibits inhibin B-specific binding and restricted gonadotrope expression. 2 TGFBR3L transcription is controlled by two key mechanisms: steroidogenic factor 1 (SF-1) directly activates TGFBR3L via conserved promoter elements, and gonadotropin-releasing hormone (GnRH) induces transcription through early growth response 1 (EGR1) binding. 1 2 These transcriptional regulators act synergistically to establish gonadotrope-specific expression. Immunological studies confirm TGFBR3L is a pituitary-specific protein showing membranous localization in gonadotroph cells and gonadotroph tumors, with expression correlating positively to FSH and luteinizing hormone. 3 Outside reproductive function, a TGFBR3L promoter polymorphism (rs11669203) associates with neuroblastoma risk in pediatric patients, with elevated TGFBR3L expression correlating with poor survival. 4 Additionally, TGFBR3L expression decreases during fetal ovary development and may relate to polycystic ovary syndrome pathogenesis. 5