Electrophoretically distinct forms of uridine kinase in the rat. Tissue distribution and age-dependence.

By the use of polyacrylamide-gel electrophoresis, uridine kinase from foetal rat liver was separated into four types designated I, II, III and IV in decreasing order of mobility towards the anode. The most anodic (type I) was found only in rapidly growing tissues, such as foetal liver and brain, postnatal spleen and tumour cells. In adult tissues, types II, III and IV were found in the kidney, and types III and IV in the spleen and the liver, whereas type IV was the sole form of uridine kinase present in the brain.