Heterodimer; heterodimerizes with PF12. May form an antiparallel heterodimer with PF12. Present on the surface of merozoite. Specifically present in asexual blood stage parasites. First detected in the trophozoite stage, 30-40 hours post-invasion (HPI) and the proteins reaches peak expression in schizont stage, 40-48 HPI. Processed into a soluble form. No visible phenotype. Parasites grow at normal rates in vitro. Does not have erythrocyte-receptor-binding ability.