Figure 1.

FAMIN Is a Purine-Nucleoside-Metabolizing Enzyme

(A) Metabolomic library of HepG2 cells after transfection with FAMIN siRNA. Representative total mass spectra (left) separated by molecular weight (m/z), chromatography retention time, and relative levels (right).

(B) Change in relative metabolite levels in the library after incubation with recombinant FAMIN^254I or protein buffer control, depicted as volcano plot with unadjusted p values. Red dots, candidate substrates and products whose abundance decreased (a–c) or increased (d–f; n = 3 independent reactions).

(C) Representative extracted chromatograms for candidate substrates (top) and products (bottom) by using normalized peak intensity for each given m/z value.

(D) Representative mass spectra and extracted chromatograms for compound a and corresponding authentic standard.

(E) Levels of adenosine, inosine, hypoxanthine, and ribose-1-phosphate (R1P) within the metabolomic library incubated with FAMIN^254I or protein buffer control (n = 3, mean ± SEM).

(F) Levels of adenosine within the metabolomic library incubated with 0.1–100 μg of FAMIN^254I or protein buffer control (n = 3, mean ± SEM).

Data representative of at least 3 independent experiments. ^∗p < 0.05 and ^∗∗p < 0.01 (unpaired, two-tailed Student’s t test).