Figure 2. Activity of AS160 GAP domain against the 18 Rab proteins.

The GAP assay was carried out as described in the Experimental section and shown in Figure 1. The data show the increase in the percentage of the total radioactivity in GDP between 0 and 15 min for the Rab alone and the Rab plus the AS160 GAP domain. In addition, for any Rab that appeared to be a GAP substrate, as well as most of the others, the assay was also performed with the GAP R/K mutant. In the case of Rab5A, the data are for 3 min, rather than 15 min, due to the high intrinsic GTPase activity of this Rab.