Protein insertase that mediates insertion of transmembrane proteins into the mitochondrial outer membrane (PubMed:36264797). Catalyzes insertion of proteins with alpha-helical transmembrane regions, such as signal-anchored, tail-anchored and multi-pass membrane proteins (PubMed:36264797). Does not mediate insertion of beta-barrel transmembrane proteins (PubMed:36264797). Also acts as a receptor for the truncated form of pro-apoptotic BH3-interacting domain death agonist (p15 BID) and has therefore a critical function in apoptosis (By similarity). Regulates the quiescence/cycling of hematopoietic stem cells (HSCs) (By similarity). Acts as a regulator of mitochondrial fusion, essential for the naive-to-primed interconversion of embryonic stem cells (ESCs) (By similarity). Acts as a regulator of lipid homeostasis and has a regulatory role in adipocyte differentiation and biology (By similarity). {ECO:0000250|UniProtKB:Q791V5, ECO:0000269|PubMed:36264797}. This is the function of Ensembl gene identifier ENSG00000109919 (MTCH2, mitochondrial carrier 2).