Mutations of the FAA polypeptide. The wild-type FAA protein (1455 amino acids), predicted from the cloned FAA cDNA,108 109 is shown schematically at the top. The protein contains a putative bipartite nuclear localization signal at the N-terminus and an incomplete leucine zipper. The indicated FAA alleles are shown at the left. The mutant FAA polypeptides, predicted by the mutant alleles, are shown schematically. A mutant protein with an in-frame deletion is predicted by the 1514(del)156 allele. Detection of these predicted mutant proteins in FA(A) cells awaits the generation of an FAA specific antiserum.