Figure 5. GAP activity of purified MSP1D1-AtRGS1 complex.

250 nM of purified AtGPA1 was pre-incubated with [γ-³²P] GTP in ice cold buffer. Single turnover GTPase assay were initiated by the addition of GTPγS containing buffer with the indicated concentration of purified RGS1 box (A) or purified sequential expressed AtRGS1 (B). Duplicated reactions were stopped by ice cold quench buffer at the indicated time points. Each experiment was repeated at least once. The data were fit to exponential One-phase association functions using GraphPad Prism version 5.0 and the calculated rates shown in the tables to the right. K value is the rate constant of the reaction. ΔK is the increase caused by RGS1 box or full-length AtRGS1.