Fig. 2. Genomic organization of the zebrafishtfap2a locus. (A) Genetic map of linkage group 24 (LG24) showing the position of mont blanc/tfap2a in relation to some SSLP markers. (B) The genomic organization of the zebrafish tfap2a gene; exons Ia, Ib and Ic represent alternative first exons for isoforms 1, 2 and 3. (C) Identification of the mob^m819 mutation revealed an A to T transition (red) at the beginning of exon V, which introduces a stop codon (black box) and a DraII restriction site (green with red T). (D) RFLP was used for linkage analysis. Intron primers P1 and P2 give rise to a 360 bp PCR product. Amplified mutant DNA can be cleaved by DraII into 123 bp and 237 bp fragments. (E) The stop codon causes a truncation of Tfap2a at amino acid 264. The truncated protein lacks the dimerization and DNA binding domain (DDB, indicated in green). 1a, 1b and 1c are alternative first exons; M, 100 bp marker; TA, transactivation domain; und., undigested PCR product.