Tyrosine aminotransferase induced in cells genetically and epigenetically deficient for this enzyme

Mice homozygous for lethal deletions around the albino (c) locus are deficient for several liver-specific enzymes, including tyrosine aminotransferase (TAT). The structural gene coding for this enzyme appears to be intact in these mutants and can be “activated” in homozygous mutant mouse liver-rat hepatoma cell hybrids. The present study demonstrates that the mouse form of TAT can also be induced in both normal and mutant mouse skin-rat hepatoma cell hybrids. Thus, a liver-specific enzyme is expressed in skin cells, both normal and mutant, the normal differentiated state of which excludes TAT expression.