Essential component of the TIM23 complex, a complex that mediates the translocation of transit peptide-containing proteins across the mitochondrial inner membrane (By similarity). Plays an essential role in early embryonic development. Component of the TIM23 complex at least composed of timm23, timm17 and timm50. The complex interacts with the timm44 component of the PAM complex (By similarity). Mutants show various developmental defects including reduced tail circulation, and smaller head, eye and body. Belongs to the Tim17/Tim22/Tim23 family.