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. Seems to control the nucleotide-dependent binding of mtHSP70 (hsp70-5) to substrate proteins (By similarity). Component of the PAM complex, at least composed of hsp70-5/ssc1, grpe/mge1, tim44, un-4/pam16, pam17 and tim14/pam18. Belongs to the GrpE family.