Table 1.
Structure-function analysis of human G6PT
Ad-G6PT | Microsomal G6P Uptake Activity | Proteoliposomal G6P Uptake Activity | Proteoliposomal Pi Uptake Activity |
---|---|---|---|
Mock | 0.085 ± 0.003 | 0.31 ± 0.04 | 9.3 ± 0.3 |
Wild-type | 0.332 ± 0.002 (100) | 1.52 ± 0.01 (100) | 112.7 ± 0.4 (100) |
K240C | 0.125 ± 0.006 (16.2) | 0.50 ± 0.02 (15.7) | 28.2 ± 0.5 18.3) |
K240R | 0.219 ± 0.008 (54.3) | 0.90 ± 0.01 (48.8) | 63.2 ± 1.2 (52.1) |
H366D | 0.131 ± 0.006 (18.6) | 0.55 ± 0.03 (19.8) | 29.7 ± 0.8 (19.7) |
V369K | 0.104 ± 0.003 (7.7) | 0.48 ± 0.03 (14) | 19.1 ± 0.3 (9.5) |
H366D/V369K | 0.105 ± 0.004 (8.1) |
Microsomal G6P uptake activity (nmol/mg microsomal protein/3 min) was analyzed in microsomes isolated from COS-1 cells co-infected with Ad-G6Pase-α and Ad-G6PT or an Ad-G6PT mutant. Proteoliposomal G6P or Pi uptake activity (nmol/mg proteoliposomal protein/9 min) was analyzed in proteoliposomes reconstituted from detergent solubilized COS-1 microsomal membrane extracts expressing a wild-type or a mutant Ad-G6PT and were loaded with 50 mM Pi as described under Materials and methods. Results shown are from 3 independent experiments, each point determined in triplicate. Values represent mean ± SEM. Numbers in parentheses represent the percentage of wild-type transport activity.