The yeast clathrin adaptor-interacting protein Irc6 is an orthologue of human p34, which is mutated in the inherited skin disorder punctate palmoplantar keratoderma type I. Irc6 and p34 bind to clathrin adaptor complexes AP-1 and AP-2 and are members of a conserved family characterized by a two-domain architecture.
Mutations in the DNA binding region of XPA were from patients with the more severe disease often associated with neurological complications, whereas mutations in the C-terminal end of the protein, which interacts with the TFIIH transcription factor, were from patients with milder skin disease only.