Essential for the invasion of host erythrocytes by blood stage merozoites (PubMed:25583518, PubMed:27374406, PubMed:25296023, PubMed:22080952, PubMed:18827878, PubMed:19000690, PubMed:31204103, PubMed:28186186, PubMed:28409866). By binding P113 at the surface of the merozoite and human BSG/basigin on the erythrocyte membrane, leads to the establishment of a tight junction between the merozoite and host erythrocyte membranes (PubMed:25583518, PubMed:27374406, PubMed:25296023, PubMed:22080952, PubMed:28186186). In addition, the interaction with BSG results in BSG dimerization which triggers an increase in intracellular Ca(2+) in the erythrocyte (PubMed:27374406, PubMed:28409866). This essential step leads to a rearrangement of the erythrocyte cytoskeleton required for the merozoite invasion (PubMed:28409866). Forms a complex composed of RH5, P113 and human BSG/basigin; the complex bridges the merozoite and host erythrocyte membranes (PubMed:28186186). Within the complex, interacts (via C-terminus) with human BSG/basigin isoform 2 (via the extracellular domain); the interaction is independent of BSG glycosylation status (PubMed:22080952, PubMed:25296023, PubMed:28186186, PubMed:24297912, PubMed:30542156, PubMed:28096331). Weakly interacts with P.troglodytes BSG but not with G.gorilla BSG (PubMed:24297912). Also, interacts (via N-terminus) with P113; the interaction tethers RH5 to the merozoite membrane (PubMed:28186186). 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:28186186, PubMed:21909261, PubMed:30542156). Within the complex, interacts with CyRPA (PubMed:28186186, PubMed:30542156). CyRPA recruits RIPR to the 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, localizes in the rhoptry lumen (PubMed:19000690, PubMed:21909261, PubMed:28409866). During merozoite invasion of host erythrocytes, secreted at the merozoite apical surface where it colocalizes with CyPRA and RIPR at the interface between the merozoite and the erythrocyte (PubMed:19000690, PubMed:21909261, PubMed:25583518, PubMed:27374406). Expressed during parasite asexual blood stages, specifically at the schizont stage and in free merozoites (at protein level). Cleaved into a 45kDa form during merozoite invasion of host erythrocyte. 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.