Table S4.

The hyperactive α13-helix + β-hairpin variant GCK is not inhibited by recombinant rat GKRP

Condition	Rate, nmoles G6P/min
α13-helix + β-hairpin	40.7 ± 0.1
α13-helix + β-hairpin with sorbitol-6-phosphate (500 μM)	41.9 ± 0.3
α13-helix + β-hairpin with sorbitol-6-phosphate (500 μM) and GKRP (10 μM)	45.2 ± 0.3

All rates are the average of two trials ± SD. Rates were determined via LDH/PK linked enzyme assay as described in Materials and Methods in the presence of 5 mM glucose and 22 nM of the α13-helix + β-hairpin variant GCK. Under identical conditions, wild-type GCK activity is reduced 20% by the presence of GKRP and sorbitol 6-phosphate.