Sequence Motifs in MADS Transcription Factors Responsible for Specificity and Diversification of Protein-Protein Interaction
Figure 5
Mechanism of generating protein-protein interaction diversity by shifting intron/exon borders.
(A) After a duplication of a gene or in the case of alternative splicing, a shift of an intron/exon border can modify a protein interaction motif which overlaps or is close to such a border. Top panel, schematic illustration of this process. Line indicates gene sequence, grey bars indicate exons, and colored bars indicate predicted interaction motifs. Bottom panel, part of a protein sequence alignment for the Arabidopsis MADS domain protein SHORT VEGETATIVE PHASE (SVP1) and an identified alternatively spliced SVP form named SVP3. A predicted interaction motif in SVP1 which is almost completely spliced out in SVP3 is shown in red. Two grey bars indicate the two adjacent exons. (B) Predicted interaction motifs can be either close to an intron/exon border (indicated by red motif) or far away from the intron/exon border (green motif). Bars in the graph indicate average number of Arabidopsis MIKC MADS proteins in which predicted interaction motifs occur for two different motif groups: motifs that are located close to the intron/exon border (<3 amino acids distance, red) occur on average in a few proteins only, and motifs that are located far away from the border (> = 3 amino acids distance, green) occur in many proteins.