Essential for the invasion of host erythrocytes by blood stage merozoites (PubMed:22593616, PubMed:25583518, PubMed:27374406, PubMed:28195530, PubMed:28195038). Required for the assembly of the PfRH5 adhesion complex (or invasion complex) composed of CyRPA, RH5 and RIPR at the interface between the merozoite and the host erythrocyte membranes (PubMed:25583518, PubMed:28186186, PubMed:28195530, PubMed:28195038, PubMed:30542156). This facilitates the binding of RH5 to host receptor BSG/basigin, which leads to the establishment of a tight junction between the merozoite and host erythrocyte membranes and allows Ca(2+) release into the erythrocyte (PubMed:27374406, PubMed:28186186, PubMed:30542156). Component of the PfRH5 adhesion complex composed of 1 copy of CyRPA, RH5 and RIPR; the complex is formed during merozoite invasion of host erythrocytes specifically at the interface between the parasite and host membranes (PubMed:25583518, PubMed:27374406, PubMed:30542156). Following the establishment of the junction between the merozoite and the erythrocyte, CyRPA dissociates from the complex (PubMed:30542156). Within the complex, interacts with RH5 and RIPR (PubMed:28195530, PubMed:30542156). CyRPA recruits RIPR to RH5-P113-BSG complex; the formation of the PfRH5 adhesion complex increases the affinity of RH5 for BSG and probably leads to the release of RH5 from P113 while maintaining the interaction of the PfRH5 adhesion complex with BSG (PubMed:28186186, PubMed:30542156). In late schizonts, colocalizes with RIPR in the microneme lumen (PubMed:22593616, PubMed:25583518, PubMed:27374406). During merozoite invasion of host erythrocytes, secreted at the merozoite apical surface where it colocalizes with RIPR and RH5 at the interface between the merozoite and the erythrocyte (PubMed:25583518, PubMed:27374406). Expressed during parasite asexual blood stages, specifically at the schizont stage, in free merozoites, and at the very early ring stage but not in late ring and early trophozoite stages (at protein level). N-glycosylated. Conditional knockdown causes loss of cell growth and severely impairs merozoite invasion of erythrocytes. Attachment to and deformation of erythrocyte membrane is normal, however the subsequent step, which triggers an increase in Ca(2+) from the attached merozoite into the erythrocyte, is impaired. Potential candidate for the development of parasite blood stage vaccines. In vitro and in vivo, induces neutralizing antibodies capable of inhibiting merozoite invasion of host erythrocytes. CyRPA was thought to be GPI-anchored to the merozoite membrane (PubMed:25583518). However, a subsequent report shows that this was not the case (PubMed:27374406). CyRPA shares structural homology with sialidases, however the 3 conserved arginine residues involved in substrate binding and the nucleophilic tyrosine residue are not conserved. Does not have sialidase/neuraminidase activity in vitro.