Xeroderma Pigmentosum, Complementation Group F (XPF)

The predicted human ERCC4 protein has 2 leucine zipper domains in the N-terminal region. ERCC4 protein expressed in mammalian cells has a molecular mass of 110-kD by Western blot analysis. In cells of an XPF patient, ERCC4 protein levels were less than 5% of normal. Nucleotide excision repair (NER), which is defective in xeroderma pigmentosum, involves incision of a DNA strand on each side of a lesion.

There is evidence that the 2 incisions made during NER are catalyzed by separate DNA endonucleases. In humans, XPG endonuclease makes the 3-prime incision relative to the lesion. The ERCC4 gene encodes a protein that together with ERCC1 make up the ERCC1-XPF 5-prime endonuclease.