GRPEL2 is an 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. GRPEL2 seems to control the nucleotide-dependent binding of mitochondrial HSP70 to substrate proteins. GRPEL2 stimulates ATPase activity of mt-HSP70. GRPEL2 may also serve to modulate the interconversion of oligomeric (inactive) and monomeric (active) forms of mt-HSP70.