ARH protein with PTB domain: Gene structure (A), predicted amino acid sequence (B), and location of mutations in ARH protein (C). (A) ARH is encoded by nine exons and spans ~25 kb. Filled rectangles, exons; lines, introns. (B) The predicted amino acid sequences of human, mouse, and Xenopus ARH. Numbers to the right correspond to human sequence. The alignment of the inferred amino acid sequences displays 67% identity among the three proteins. The regions of amino acid identity are boxed. ARH has a highly conserved PTB domain at the amino terminus (indicated by blue shading, 89% identity). (C) Schematic representation of ARH showing the location of the mutations identified in this study.