The amino terminal two-thirds of FANCG (amino acids 1-428) is required for FANCA binding.

(A) Schematic representation of wild-type and mutant forms of FANCG. Seven FANCG polypeptides contain an HA-epitope tag at their amino terminus. FANCGΔexon13 (modeled from a splice variant observed by RT-PCR from normal human cells that results from exon 13 skipping) has 551 amino acids plus 5 altered amino acids. FANCG1749ΔA (derived from a known FA-G patient) has 583 amino acids plus 9 altered amino acids resulting from a frame shift. Results of binding studies are summarized as (+) and (−). Lz, leucine zipper. (B) COS cells were cotransfected with the indicated HA-FANCG mutant cDNAs and the full-length (wild-type) FANCA cDNA. Immunoprecipitation (lanes 1-5, 11-13, and 17-19) was performed with an anti-FANCA antiserum. Whole cell extracts (WCE) were analyzed in lanes 6-10, 14-16, and 20-22. Immunoblotting was done with an anti-HA monoclonal antibody. In lane 19, HA-FANCG 1-428 comigrated with the immunoglobulin heavy chain at 50 kD. * Data not shown.