Fine organization of repetitive domains with Ua and Ub as basic units, and B1 and B2 as boundary elements. The patterns used here are defined as those in GCG FindPatterns: Ua (red), (GGNGCN){0,}GGNTCW (no mismatch); Ub (blue), (GGNGCN){0,}GGNTAY (no mismatch); B1 (black), GGAGCAGGAGCAGGAAGC (with one mismatch); B2 (green), GGAGCTGCCTCT (with one mismatch). (A) Distribution of Ua, Ub, B1 and B2 in the fibroin gene repetitive domains, R01–R12. (B) Enlarged figures of R01, R06 and R12. (C) Sequences of the first subdomain in R01, a typical subdomain (the third) in R06, and the last repetitive domain R12 (the 3′ end of the truncated B1-like sequence is not shown).