TBC1D9B functions as a GTPase-activating protein for Rab11a in polarized MDCK cells.
Bottom Line: In contrast, TBC1D9B had no effect on two Rab11a-independent pathways--basolateral recycling of the transferrin receptor or degradation of the epidermal growth factor receptor.Finally, expression of TBC1D9B decreased the amount of active Rab11a in the cell and concomitantly disrupted the interaction between Rab11a and its effector, Sec15A.We conclude that TBC1D9B is a Rab11a GAP that regulates basolateral-to-apical transcytosis in polarized MDCK cells.
Affiliation: Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261.Show MeSH
Mentions: TBC1D9B is an ∼140-kDa TBC domain–containing protein with a comparable domain architecture to Gyp2p (Figure 1A). Furthermore, the overall similarity of these proteins is reasonably high at 49% and increases to 64% when the TBC domains are assessed individually. The TBC domain of TBC1D9B contains conserved R, Y, and Q residues, which form the “R” and “Q” fingers that are critical for GTP hydrolysis in other TBC proteins (Figure 1B; Pan et al., 2006; Gavriljuk et al., 2012).
Affiliation: Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261.