DNA repair nuclease/redox regulator APEX1
endonuclease activity
Sequence analysis identifies TTRAP, a protein that associates with CD40 and TNF receptor-associated factors, as a member of a superfamily of divalent cation-dependent phosphodiesterases.
CD40 is a member of the tumor necrosis factor (TNF) receptor family. CD40-mediated signal transduction involves the recruitment of several cytoplasmic proteins and induces expression of a large number of genes. TTRAP, a novel protein that interacts with the cytoplasmic domain of CD40 and with TNF-receptor associated factors (TRAFs), has been cloned and shown to inhibit nuclear factor-kappaB activation (NF-kappaB). By using various bioinformatics-based sequence and structure analyses of proteins involved in signaling by the TNF receptor family, we found that TTRAP is a member of a superfamily of Mg(2+)/Mn(2+)-dependent phosphodiesterases. More precisely, our results suggest that TTRAP is related to the human APE1, a Mg(2+)-dependent endonuclease. This potential novel function of TTRAP raises the intriguing possibility for a role of APE1-like DNA-repair endonucleases in TNF receptor family-mediated signaling and functions.