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:8910564, PubMed:10921929). Enhances the enzymatic activity of SPC and facilitates the interactions between different components of the translocation site (PubMed:8910564, PubMed:10921929). Component of the signal peptidase complex (SPC) composed of a catalytic subunit SEC11 and three accessory subunits SPC1, SPC2 and SPC3 (PubMed:8910564, PubMed:9148931). 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). SPC associates with the translocon complex (PubMed:10921929). Interacts with SBH1 and SEB2/SBH2 (PubMed:10921929). Present with 4890 molecules/cell in log phase SD medium. Important for signal peptidase activity and cell viability at high temperatures. Belongs to the SPCS2 family.