Fig. 1. Identification and characterization of the ini1⁺ gene in S. pombe. (A) Structure of the fission yeast ini1⁺ gene encoded by the antisense strand of chromosome I located between positions 3190 and 2686 of cosmid 23H3. E1-E4 corresponds to exons 1 through 4; the number of amino acids encoded in each exon is indicated. I1-I3 refers to introns 1 through 3; the number of base pairs in each intron is indicated. (B) Alignment of Ini amino acid sequences from human, budding yeast and fission yeast using the ClustalW interactive Multiple Sequence Alignment Program from EBI (European Bioinformatics Institute, http://www.ebi.ac.uk). Identical residues are boxed in black. Conserved residues are boxed in gray.