Component of the signal peptidase complex (SPC) which catalyzes the cleavage of N-terminal signal sequences from nascent proteins as they are translocated into the lumen of the endoplasmic reticulum (PubMed:30127496). Enhances the enzymatic activity of SPC and facilitates the interactions between different components of the translocation site (By similarity). Also, regulatory component of the CSP25-plasmepsin PMV complex which cleaves the pentameric localization motif RxLxE/Q/D (termed Plasmodium export element (PEXEL)) located downstream of the N-terminal secretory signal sequence of several proteins (PubMed:30127496). Component of the signal peptidase complex (SPC) composed of a catalytic subunit SEC11/SPC21 and three accessory subunits SPC25, SPC3/SPC22, SPC1/SPC12 (PubMed:30127496). The complex induces a local thinning of the ER membrane which is used to measure the length of the signal peptide (SP) h-region of protein substrates (By similarity). This ensures the selectivity of the complex towards h-regions shorter than 18-20 amino acids (By similarity). Within the complex, interacts with SEC11/SPC21 (PubMed:30127496). Component of a complex composed of SPC25 and PMV; the interaction is mediated via the transmembrane domains (PubMed:30127496). The complex interacts with the SEC61 channel-forming translocon complex and is involved in the recognition and import of PEXEL motif-containing proteins into the ER for subsequent export (PubMed:30127496). Partially colocalizes with plasmepsin PMV in the endoplasmic reticulum (PubMed:30127496). Partially colocalizes with SEC11/SPC21 in the endoplasmic reticulum (PubMed:30127496). Expressed during the asexual blood stage; expression is low at the ring stage and then increases through the trophozoite and schizont stages (at protein level). Causes a severe growth defect in host erythrocytes (PubMed:30127496). Export of protein containing a PEXEL motif, including PIESP2, PTP3 and PTP2 is severely reduced at the ring and trophozoite stages (PubMed:30127496). Similarly, export of RESA is reduced at the schizont stage (PubMed:30127496). Belongs to the SPCS2 family.