Fig. 6. The HLR gene encodes RPT2a, a homolog of the 26S proteasome subunit. Map-based cloning of the HLR gene. (A) Physical and genetic map of the HLR gene on chromosome 4. Molecular markers and their positions are shown above the line. Values under the lines indicate the frequency of recombinants. The bipolar arrow indicates the 45 kb region sequenced to find the mutation site in hlr-1. (B) Schematic structure of the HLR gene. Black and white rectangles indicate the protein coding regions and untranslated regions (UTRs), respectively. The 13 bp deletion found in hlr-1 is shown. (C) Alignment of the deduced amino acid sequence of HLR with selected homologous proteins. Identical residues are shown in white on a black background. Major motifs and mutation sites found in the hlr mutant are shown. Orthologous proteins are from Oryza sativa (PRS4-ORYSA), Drosophila melanogaster (PRS4-DROME), Homo sapiens (PRS4-HUMAN) and Saccharomyces cerevisiae (PRS4-YEAST).