Soluble tankyrase located in cytosol of human embryonic kidney cell line 293.

We studied the subcellular localization of tankyrase in primary and immortalized human cell cultures. In embryonic kidney cell line 293 the enzyme was excluded from the nuclei and distributed in fractions of soluble cytosolic proteins and low-density microsomes. Newly revealed cytosolic tankyrase in its poly(ADP-ribosyl)ated form was passed through a Sepharose 2B column and eluted as an apparently monomeric protein. The cytosolic localization of the enzyme correlated with its relatively high activity in the 293 cell line in comparison to eight other studied cell types.