D-glycero-alpha-D-manno-heptose 1-phosphate + GTP + H(+) => GDP-D-glycero-alpha-D-manno-heptose + diphosphate
d-glycero-alpha-d-manno-heptose 1-phosphate + gtp + h(+) => gdp-d-glycero-alpha-d-manno-heptose + diphosphate