The exon 11b encoded sequence is a functional SBS. A) Comparison of exon 11b encoded protein sequence (containing SBS1') with those of other vertebrate SBS-encoding dystrobrevin exons. Vertical dotted lines delimit the 15-residue pan-SBS consensus, and specific SBS consensus sequence logos are presented below the alignment. Arrow at top indicates the leucine mutated to proline in the yeast two-hybrid constructs. B) Schematic diagram showing observed α-dystrobrevin SBS isoform repertoires in various vertebrates. 'a*' is a one-SBS isoform seen in zebrafish, where the 'a' form is not observed. C) Yeast two-hybrid analysis of the interactions between mutant and wildtype α-dystrobrevin constructs and full-length β1-syntrophin. Fine isoforms are shown as 'a', 'b', 'c', 'd'; mutant status of respective SBSs is shown as superscript 'w' (wild-type) or 'm' (mutant) and by green and red boxes, respectively. Growth on AHLT- plates was scored as '-' (0-10 colonies), '+' (10-100), '++' (100-1000) or '+++' (>1000).