This family includes the NTF2-like Delta-5-3-ketosteroid isomerase proteins.
Nuclear transport factor 2 (NTF2) is a homodimer which stimulates efficient nuclear import of a cargo protein. NTF2 binds to both RanGDP and FxFG repeat-containing nucleoporins. NTF2 folds into a cone with a deep hydrophobic cavity, the opening of which is surrounded by several negatively charged residues. RanGDP binds to NTF2 by inserting a conserved phenylalanine residue into the hydrophobic pocket of NTF2 and making electrostatic interactions with the conserved negatively charged residues that surround the cavity [PUBMED:9533885].