STUDY OF THE COPPER-BINDING PROTEINS IN LIVER AND KIDNEY TISSUE OF NEONATAL NORMAL AND MOTTLED MUTANT MICE

The Cu2+-binding proteins from liver and kidney tissue of 7 or 8 day old brindled (Mobr) mice and their normal littermates were compared. Separation over Bio-Gel P-10 showed that the differences in the Cu2+ content of mutant tissues were largely associated with a low MW protein fraction (MW 14,500). Further purification of this low MW fraction by anion-exchange chromatography revealed 4 subfractions. The Cu2+ content of each subfraction reflected the Cu2+ status of the tissue or origin; the Cu2+ contents of the mutant kidney subfractions were elevated and those of the mutant liver were depressed compared with normal. The protein contents of the subfractions were less variable and did not reflect the differing Cu2+ contents. Amino acid analysis of the 4 subfractions from CuCl2-treated mutant and normal animals revealed close similarities. The proteins showed high Gly, Glu, Ser, Ala and Lys contents and a rather variable Cys content. Differences were apparent in the normal liver subfractions, which showed a higher Cys content and lower Glu content than did either the mutant liver or normal and mutant kidney subfractions. These observations, together with the recorded presence of aromatic amino acids, indicated that these proteins are not thioneins. (The bindled mouse is an animal model for human Menkes kinky-hair syndrome.).