MOLECULAR-CLONING OF 3 SULFOTRANSFERASE CDNAS FROM MOUSE-LIVER

Sulfate conjugation plays an important role in the biotransformation of not only xenobiotics but also many endogenous substances. Sulfotransferases, the enzymes that are responsible for this process, exist as a superfamily of genes. It has long been recognized that significant species differences exist among drug and carcinogen metabolizing enzymes such as cytochrome P450. Species differences in both regulation and catalytic activities of sulfotransferases may also exist. To investigate this, we conducted cDNA cloning and cDNA expression studies of sulfotransferase in the mouse. Three sulfotransferase cDNA clones were isolated from a female B6CBA mouse liver. Two of the clones, mST(a1) and mST(a2), were highly homologous to each other. Alignment of mST(a1) and mST(a2), cDNAs' nucleotide sequences with those of other sulfotransferase cDNAs revealed the greatest sequence identity with the rat STsmp cDNA. This analysis suggests that mST(al), mST(a2) and rST(smp) cDNAs are derived from orthologous genes belonging to the alcohol/hydroxysteroid sulfotransferase gene family. The third clone, mST(pl) showed high identity to rSTp, hST(p1), hST(p3), and rST(p1C1), suggesting that mST(p1) belongs to the phenol family.