The structure of SULT2B1b complexed with pregnenolone and PAP (Protein Data Bank code: 1Q20), containing the polypeptides from Ser18 (N-terminus) to Glu311 (C-terminus), was shown by ribbon diagram. Pregnenolone (Preg) and PAP molecules in the structure are shown by bond structures. Segement-1, Segment-2 (Loops 3), Segment-3, and loop-2 refer to Arg93-Gly109 (dark blue), Asn252-Ala271 (magenta color), Val41-Ser45 (Green), and Ile-Thr171 (orange color) previously reported to form a gate for substrate entry [Cook et al. 2012, Tibbs et al. 2015]. Side chains of the amino acid residues involved in the SULT2B1b cSNPs, Pro69, Gly72, Thr73, Arg147, Asp191, Arg230, Ser244, Arg274, and Gly276 are indicated by bond structures (red color).