May play a role in host cell invasion. Initially localizes to micronemes, specialized secretory organelles of apicomplexan parasites important for host cell invasion. Relocalizes to the surface membrane upon host invasion. Readily detected in oocysts (at protein level). Specifically up-regulated in sporozoites, but not in tachyzoites and bradyzoites. Proteolytically cleaved within its transmembrane domain, releasing a soluble form from the cell surface. Belongs to the apicomplexan parasites AMA1 family.