Figure 1.

QH6 gene structure showing sites and sizes of exons and introns, predicted conserved domains, and positions of designed primers. M, methionine as a translation start signal; RR(X)₈W, conserved tandem arginine as a transit peptide signal (R⁴⁸R⁴⁹), and a conserved tryptone (W⁵⁸) at the 9th residue after RR. The conserved RXR domain (R³⁰⁰D³⁰¹R³⁰²) used to direct the diphosphate anion away from the reactive carbocation after ionization and the DDXXD (D³³⁷D³³⁸V³³⁹Y³⁴⁰D³⁴¹) domain for divalent cation (typically Mg²⁺ or Mn²⁺)-assisted substrate binding were both found at the 4th exon. Sequences of primers are listed in Supplementary Table S1.