Essential component of the PAM complex, a complex required for the translocation of transit peptide-containing proteins from the inner membrane into the mitochondrial matrix in an ATP-dependent manner. In the complex, it is required to stimulate activity of mtHSP70 (SSC1) (By similarity). Heterodimer with PAM16. Component of the PAM complex, at least composed of mtHsp70, MGE1, TIM44, PAM16, PAM17 and PAM18 (By similarity). The J domain is essential for co-chaperone activity and mediates the heterodimerization with the J-like domain of PAM16. Belongs to the TIM14 family.