On the functional heterogeneity of UDP-glucuronyl transferase of mouse liver microsomes.

Fractionation of sodium cholate solubilized microsomes from mouse liver on Sepharose CL-48 yielded three protein peaks with UDP-glucuronyltransferase activities. Of these three peaks, only peak II contained activities towards all the substrates tested: p-nitrophenol, 1-naphthol, morphine, testosterone and estrone. These glucuronyltransferase activities could not be dissociated by further chromatography on DEAE-Sepharose CL-6B and isoelectric focusing. The results show the presence of a functional form of glucuronyltransferase with a wide substrate specificity, and indicate that in addition, other forms with narrower studied specificities may also be present in mouse liver microsomes.