Fig. 1. Genetic, sequence and western blot analysis of scraps (anillin) alleles. (A) An allelic series of scraps alleles from complementation data in Table S1. Genes with a stronger phenotype are on the right. (B) Schematic of Anillin domain structure; MY, Myosin II-binding region; ACT, F-actin binding region; AH, Anillin homology region; PH, pleckstrin homology domain, and (Septin binding) the region required for Anillin recruitment of septins to F-actin bundles. Positions of amino acid substitutions in anillin mutant alleles are shown below. (C) Sequence alignment near the N terminus of the Anillin PH domain. Sequences from Drosophila, human, Xenopus and C. elegans are shown with a predicted secondary structure below. The amino acid changes for the three strong scraps alleles are indicated above. Note that the V to S change at the beginning of the PH domain is present in all Schupach/Wieschaus alleles sequenced (red arrowhead). (D) Western blot analysis of maternal effect alleles. Embryo extracts from wild-type and three different maternal allelic combinations were probed with antibodies to Anillin and Actin.