TABLE 1.
Summary of V1-ATPase inhibition experiments
| V1 complex expressed in yeast | Bacterially expressed (H subunit added) | H subunit bound? | % V1 (-H) (ATPase activity) |
|---|---|---|---|
| V1(-H) | None | None | 100 |
| V1(-H)/H-NT | None | H-NT co-isolates with V1 | 26 |
| V1(-H)/H-CT | None | None | 100 |
| V1(-H) | Full-length H | H binds tightly through repurification | 20 |
| V1(-H) | H-CT | Very little detected after repurification | 38 |
| V1(-H) | H-CT (+MgATP) | More H-CT retained after repurification | NDa |
| V1(-H)/H-NT | Full-length H | H subunit partially displaces H-NT | 5 (20)b |
| V1(-H)/H-NT | H-CT | ND | 14 (55)b |
a
ND, not determined.
b
Activity relative to isolated V1(-H)/H-NT complexes (from Fig. 3) is shown in parentheses. To compare the overall activity and inhibition of these complexes to V1(-H) complexes, the % activity in the V1(-H)/H-NT complexes as isolated (26%) was multiplied by the proportion of the activity remaining after addition of expressed H or H-CT.