Figure 3.

Rice and agave activases form hetero-oligomers displaying intermediate functionality but subunit-specific thermostability. A and B, Rubisco activation assay (A) and ATPase assay (B) performed using 5 µm activase protomer (2.5 µm + 2.5 µm for AtRcaβ + OsRcaβ). ATPase is given per active site. C, Evidence for hetero-oligomerization. AtRcaβ was mixed with increasing amounts of ATPase inactive OsRcaβD173A, incubated for 10 min, and assayed for ATPase activity. D, Incubation at 45°C restores ATPase activity of impaired hetero-oligomers to levels of AtRcaβ wild type. C and D, ATPase activity was calculated as turnovers per wild-type active site. Error bars indicate mean and sd of independent experiments (A, n = 5–42; B and D, n = 4–7).