Figure 4.

Genomic structure of myb12 alleles. A, Schematic overview and partial structure of the third exon of the originally isolated myb12∷En-1 line (AT123). White boxes symbolize exons and the connecting lines introns. Numerical values above exons indicate nucleotide positions relative to the transcription start site. Intron lengths are indicated. The En-1 transposon insertion took place between nucleotides at positions 869 and 870. The nucleotides of the 3-bp target sequence duplication of the En-1 transposon are highlighted by underscore. The arrow upside the transposon marks its orientation. B, Comparison of nucleotide and protein sequence of wild-type (MYB12) and myb12-1f alleles. Only the third exon is shown. In the genetically stable myb12-1f line the deletion of the guanidine nucleotide at position 869 leads to the premature termination of translation. The myb12-1f protein comprises only 260 amino acids compared to 370 in the wild-type case. In addition the sequence of the last seven amino acids is altered at six positions.