Fig. 1. The Drosophila MYPT gene. (A) Genomic organization of DMYPT. Exons are shown in purple and introns in blue. The start and stop codons of DMYPT, as well as the location of the two P-insertions, DMYPT⁰³⁸⁰² and DMYPT³⁷²⁷, are indicated. The sequence of DMYPT cDNA differs from the annotation of CG5891 in several places. Compared to the original annotation, we find that DMYPT has: (1) a three base pair (bp) deletion at the beginning of exon 5 (numbered after the annotation); (2) no exon 6; (3) a 48 bp insertion after exon 10; (4) a 24 bp deletion at the end of exon 15; and (5) four additional exons at the 3' end. At the amino acid level, DMYPT (GenBank accession number AF500094) is similar to CG5891 over the first 337 residues and is unrelated thereafter. (B) BLAST alignment of DMYPT with three human MYPT isoforms: 2/a, 2/b, and 1. Homologous regions are shown in red with percentages of amino acid identity and similarity indicated. DMYPT contains four ankyrin repeats highlighted in green at the N terminus of the protein. The overall homology is higher between DMYPT and HMYPT2 than HMYPT1. (C) Amino acid sequence around the inhibitory phosphorylation site threonine (asterisk in B and C). (D) A schematic drawing of the chromosome arm and deficiencies around the DMYPT locus. Deficiencies that fail to complement with DMYPT are shown in red and those that do complement are shown in green. Regions deleted in the deficiencies are marked with dashed line. The uncertain breakpoints are shown in blue.