Fig 2

(A) Structural comparison of the crystal structures of TBC1D23 rhodanese domain (yellow) and of CDC25B (gray) (PDB ID: 1qbo). (B) Comparison of the activity site of CDC25B and the corresponding region of TBC1D23. Two essential residues (C473 and R479) from the catalytic CX₅R motif of CDC25B are shown and labeled with black font. The corresponding residues (C399 and R405) in TBC1D23 are labeled in gold font. The SO₄²⁺ found in the catalytic site of CDC25B is colored in magenta. (C) The phosphatase activity of CDC25B WT, C473S, and TBC1D23 (aa1–460). pNPP was utilized as substrates. The reaction was carried out at 25 °C, and absorbance at 405 nm was monitored. Data are from three replicate experiments (mean ± S.D.), and the numerical data are included in S1 Data. (D) The sulfurtransferase activity of TSTD1 WT, C79S, and TBC1D23 (aa1–460). (E) H₂S formed by the reaction of thiosulfate and GSH was determined in the lead sulfide assay, and absorbance at 390 nm was monitored. Data are from three replicate experiments (mean ± S.D.), and the numerical data are included in S1 Data. aa, amino acid; GSH, glutathione; PDB, Protein Data Bank; pNPP, disodium 4-nitrophenyl phosphate; TSTD1, thiosulfate sulfurtransferase like domain containing 1; WT, wild type.