The mouse gene coding for ribosomal protein L23 (Rpl23 )has been fully sequenced,including 580 bp of the 5 ) upstream region.The 5-kb gene comprises 5 exons and con- tains an unusually long (3,153 bp)third intron.The gene was mapped to the distal region of mouse chromosome 11,homolo- gous to human chromosome 17q21 .q22.