Molecular cloning of a novel rat liver dopa/tyrosine sulfotransferase

In a previous study, we have purified a novel rat liver Dopa/tyrosine sulfotransferase. The purified enzyme was demonstrated to be a 33 kDa protein capable of catalyzing the sutfation of various Dopa and tyrosine isomers. The intact enzyme was found to be N-blocked when subjected to N-terminal sequencing. Three internal partial ami no acid sequences were obtained by analyzing its proteolytic fragments. These partial amino acid sequences were found to be identical to those present in a cloned ST1B1 sulfotransferase reported by Yamazoe et al. [Chemico-Biological Interactions (1994) 92, 107], but distinct from the homologous sequences of all other known sulfotransferases. Using degenerate oligonucleotides designed based on the ST1B1 deduced amino acid sequence as primers in a reverse transcriptase-polymerase chain reaction (RT-PCR), we have prepared a 452-base pair PCR product for use as a probe in screening a rat liver Lambda ZAP II cDNA library. The deduced amino acid sequence of a full-length cDNA isolated from the cDNA library confirmed the identity of the Dopa/tyrosine sulfotransferase as a new type of aryl sulfotransferase, being different from that of the ST IB 1 enzyme by a glycine residue, instead of a glutamic acid residue, at position 68. Upon transfection of COS-7 cells with an expression vector (pMSG.CMV) harboring the full-length cDNA, a 33 kDa protein displaying enzymatic and immunological properties similar to those of the purified Dopa/tyrosine sulfotransferase was expressed.