G protein-coupled receptor for follitropin, the follicle-stimulating hormone. The activity of isoform FSH-R1 is mediated by G proteins which activate adenylate cyclase (PubMed:10527886, PubMed:9364440). Isoform FSH-R2 and isoform FSH-R3 also bind FSH, but this does not result in activation of adenylate cyclase (PubMed:10527886, PubMed:9364440). Isoform FSH-R3 may be involved in calcium signaling (PubMed:10527886). Through cAMP production activates the downstream PI3K-AKT and ERK1/ERK2 signaling pathways (By similarity). Homotrimer. Functions as a homotrimer binding the FSH hormone heterodimer composed of CGA and FSHB (By similarity). Interacts with ARRB2 (By similarity). Interacts with APPL2; interaction is independent of follicle stimulating hormone stimulation (By similarity). Isoform FSH-R3 is expressed in ovary and testis, but not in kidney (at protein level). N-glycosylated; indirectly required for FSH-binding, possibly via a conformational change that allows high affinity binding of hormone. Sulfated. Belongs to the G-protein coupled receptor 1 family. FSH/LSH/TSH subfamily.