The effect of isoproterenol upon the activity and intracellular distribution of pyrimidine nucleoside kinases in the mouse parotid gland.

The pyrimidine deoxyribonucleoside kinase activities were very low in the normal mouse parotid gland, while uridine kinase activity was high. Isoproterenol administration increased uridine, deoxycytidine, and thymidine kinase activities 2-, lo-, and 30-fold, the enzymes reaching maximum activity at 12 to 14, 27, and 30 hours after isoproterenol injection, respectively. DNA synthesis was maximal at 27 hours. In control glands 25 % of the deoxycytidine and thymidine kinase activities was present in a nuclear fraction and 40% of the uridine kinase activity in the microsomal fraction. Most of the remainder of their activities was present in the high speed supernatant fraction. After isoproterenol injection the activities of these enzymes in the nuclear, mitochondrial, and microsomal fractions changed only slightly, while 97% of the increased activities was present in the ~$0~01 fraction. Sedimentation of crude homogenates on sucrose gradients showed that the nuclear and cytoplasmic forms of the deoxyribonucleoside kinases had the same molecular weights, being 65,000 for deoxycytidine kinase and 70,000 for thymidine kinase. Isoproterenol produced no change in the sedimentation characteristics of deoxycytidine kinase, but three new thymidine kinase species with molecular weights of 55,000, 95,000, and 130,000 were present under varying conditions.