Gametocyte surface protein required for male/female gamete fusion. Also required for male gamete exflagellation and interaction with host erythrocytes. Heterodimer; heterodimerizes with PF45/48. Specifically expressed in gametocytes and gametes (at protein level). May be processed into a 310 kDa form as the parasite emerges from the host erythrocytes. Promising transmission-blocking vaccine candidate: targeting the protein would prevents transmission of the parasite decreasing the malaria burden (PubMed:32709983, PubMed:33741942). The LMIV230-01 transmission-blocking antibody against the 6-Cys domain 1 also binds to the heterologous P.falciparum Malian isolate 20-2217-0 which carries a 'Ser-605' polymorphism and to the heterologous St Lucia strain which carries 'Ser-605' and 'Asn-661' polymorphisms (PubMed:33741942).