Catalyzes the removal of a penultimate prolyl residue from the N-termini of peptides, such as Leu-Pro-Ala (, ). Also shows low activity towards peptides with Ala or Ser at the P1 position .
Promotes TNFRSF1B-mediated phosphorylation of MAPK8/JNK1 and MAPK9/JNK2, suggesting a function as an adapter protein for TNFRSF1B; the effect is independent of XPNPEP3 peptidase activity. May inhibit apoptotic cell death induced via TNF-TNFRSF1B signaling.
Subcellular locations: Mitochondrion, Cytoplasm
Mainly mitochondrial. Translocates to the cytoplasm following TNFRSF1B activation.
Subcellular locations: Cytoplasm
Isoform 1 and isoform 2 are widely expressed, with isoform 1 being more abundant.