DEVELOPMENTAL AND TISSUE-SPECIFIC MODULATION OF RAT GALACTOSE-1-PHOSPHATE URIDYLTRANSFERASE STEADY-STATE MESSENGER-RNA AND SPECIFIC ACTIVITY LEVELS

To assess the role of genetic regulation as a modulating factor in the variability of rat tissue galactose-1-phosphate uridyltransferase (GALT) sp act, we have determined steady state GALT mRNA and sp act in rat liver during postnatal development. Steady state GALT mRNA levels increase from birth to d 5 and subsequently decrease toward adult levels. GALT sp act mirrors the mRNA pattern. A survey of steady state mRNA and GALT sp act of several adult rat tissues revealed marked tissue differences with a good correlation of the two parameters. Liver had the highest GALT mRNA and sp act; kidney, ovary, and heart had similar but lower mRNA and sp act; skeletal muscle and testes had the least GALT mRNA and enzyme sp act. These findings suggest that genetic regulation is important in the variable expression of GALT tissue sp act.