PROSITE documentation PDOC51501 [for PROSITE entry PS51501]

Zinc finger DNL-type profile

Mitochondrial functions rely on the correct transport of resident proteins synthesized in the cytosol to mitochondria. Protein import into mitochondria is mediated by membrane protein complexes, protein translocators, in the outer and inner mitochondrial membranes, in cooperation with their assistant proteins in the cytosol, intermembrane space and matrix. Proteins destined to the mitochondrial matrix cross the outer membrane with the aid of the outer membrane translocator, the tOM40 complex, and then the inner membrane with the aid of the inner membrane translocator, the TIM23 complex, and finally mitochondrial motor and chaperone (MMC) proteins including mitochondrial heat-shock protein 70 (mtHsp70), and translocase in the inner mitochondrial membrane (Tim)15, which is also known as zinc finger motif (Zim)17 or mtHsp70 escort protein (Hep)1 in the matrix. Tim15 contains a zinc-finger motif (CXXC and CXXC) of ~100 residues, which has been named DNL after a short C-terminal motif of D(N/H)L [1,2,3].

The DNL-type zinc finger is an L-shaped molecule (see <PDB:2E2Z>). The two CXXC motifs are located at the end of the L, and are sandwiched by two-stranded antiparallel β-sheets. Two short α-helices constitute another leg of the L. The outer (convex) face of the L has a large acidic groove, which is lined with five acidic residues, whereas the inner (concave) face of the L has two positively charged residues, next to the CXXC motifs [3].

The profile we developed covers the entire DNL-type zinc finger.