Fig 2.

Exogenous expression and transaminase enzymatic activity of GPT2 mutants. a Western blot results of lysates from HeLa cells transfected to express C-terminal V5-His-tagged human GPT2 (hGPT2-V5His) or one of the GPT2 mutants P272L (previously identified loss-of-function mutation), C259R, V478Rfs*73, N271T, or Q80E. Lysates from cells transfected with empty vector were used as a control. Blots were probed with an anti-V5 antibody to detect exogenously expressed hGPT2 protein; blotting for tubulin served as a loading control. b,c Results of measurement of transaminase enzymatic activity of wild-type hGPT2 and hGPT2 mutants using lysates from HeLa cells as described in (a). Shown are a time course of hGPT enzymatic activity over a 60-min incubation period with substrate (b) and hGPT enzymatic activity measured in cell lysates after incubating with substrate for 30 min (c). n = 3 (V478Rfs*73, N271T, and Q80E), n = 6 (hGPT2, C259R, and vector control). Data are presented as means ± SEMs. ***p <0.001