Table 1. GTP loading of Rabs.

The percentage of total [α-³²P]GTP that was bound to the Rab protein was measured as described in the Experimental section. In the case of Rab5A the GTP binding was done for 1 min, rather than the usual 30 min, because at longer times considerable hydrolysis of the GTP to GDP occurred. In the case of Rab10, the value is that after removal of a portion of the unbound GTP by gel filtration (see the Experimental section).

Rab	GTP bound (%)
1A	43
2A	50
3A	43
4A	58
4B	57
5A	45
6	29
7	48
8A	50
10	40
11A	48
11B	33
14	42
18	25
21	43
27A	27
27B	70
35	33