Phenol- and monoamine-metabolizing sulfotransferases (STP and STM, respectively) are members of a superfamily of enzymes that add sulfate to a variety of xenobiotics and endobiotics containing hydroxyl or amino functional groups. To characterize related sulfotransferase genes further, we used extra-long PCR (XL-PCR) to generate three distinct sizes of amplification products from human genomic DNA or from genomic phage library clones, each of which contained sulfotransferase gene sequences. One of the PCR fragments contained a new sulfotransferase gene, STP2, corresponding to a recently published cDNA clone that encodes a sulfotransferase with catalytic specificity distinct from that of the previously described STP1 and STM. Additional upstream sequence information was obtained using a second STP2-specific XL-PCR-based approach. The STP2 gene is composed of eight exons and seven introns, with exon sizes ranging from 95 to 181 bp. Protein-coding exon lengths and locations of the splice junctions were identical to those in both the STM gene and an STP2 gene published independently by another group recently. The STP2 gene maps to a chromosomal location (16p11.2-p12) that is the same as that previously determined for both STP1 and STM. The characterization of the STP2 gene provides further insight into the organization, regulation, and multiplicity of the sulfotransferase supergene family.