Essential component of the TIM23 complex, a complex that mediates the translocation of transit peptide-containing proteins across the mitochondrial inner membrane (PubMed:30190335, PubMed:38828998). Has some phosphatase activity in vitro; however such activity may not be relevant in vivo. {ECO:0000269|PubMed:15044455, ECO:0000269|PubMed:30190335, ECO:0000269|PubMed:38828998}. [Isoform 2]: May participate in the release of snRNPs and SMN from the Cajal body. . This is the function of ENSG00000105197 (TIMM50, translocase of inner mitochondrial membrane 50).