Structure and organization of the mouse CPO gene. Two overlapping l phage clones (B6 and B8) were analyzed. The boxes show the relative sizes and positions of each exon in the mouse genome. Solid and shaded boxes indicate protein coding and untranslated regions, respectively. Recognition sites for enzymes HindIII,EcoRI, and SacI are shown. Lower lines show restriction endonuclease cleavage sites, as indicated.