Fig. 1. Specific interaction of rab1b with GM130. (A) We performed co-transformations with various rab1b mutants and a set of different rab control bait plasmids. (B) The β-galactosidase activities of the liquid lacZ assays are presented as mean ± SEM of three to six independent transformants. For the control co-transformations, the empty bait vector (pAS2-1) was used. (C) Lysates of BHK cells expressing HA-tagged GM130 were first pre-cleared with GST beads (lane 1) and then incubated with GST rab1b wt fusion proteins, pre-loaded either with GDP (lane 2) or GTPγS (lane 3) or with beads, coupled to GST rab1bS22N, GST rab1bN121I and GST rab1Q67R fusion proteins (lanes 4–6). As a control, pre-loaded GST rab6 wt beads were used (lanes 7 and 8). HA-GM130 was detected by western blotting (top panel). The amount of GST fusion proteins in the independent pull-down assays was monitored by Coomassie Blue (CBB) staining of the blot membranes (bottom panel). PM1–3, G1–3, conserved nucleotide binding motifs.