Rab22B's role in trans-Golgi network membrane dynamics.
The small GTPase Rab22B (or Rab31) has been suspected to be involved in trafficking at trans-Golgi network. However, its exact cellular localization, tissue expression profile, and functions have not been uncharacterized. Specific antibody raised against Rab22B's protein revealed that Rab22B is brain-enriched, but is also present in substantial levels in spleen and intestine. In HeLa cells, endogenous Rab22B is largely associated with the trans-Golgi network (TGN). Over-expression of a GDP-binding mutant (Rab22BSN), but not wild-type Rab22B, specifically disrupts the TGN localization of TGN46, a dynamic marker which cycles between the TGN and the plasma membrane. The TGN resident membrane protein syntaxin 16, cis-Golgi markers such as GM130 and syntaxin 5, as well as the TGN/late endosome marker mannose 6-phosphate receptor (M6PR) are not affected by Rab22BSN, neither was endosomal-TGN transport of the Shiga toxin B subunit. The disruption of TGN46 staining by Rab22BSN could be specifically attributed to a domain at the C-terminal portion of Rab22B, where its sequence deviates the most from Rab22A. Over-expression of Rab22BSN inhibits the cell surface transport of the vesicular stomatitis virus G protein. Thus, Rab22B may have a role in anterograde exit from the TGN.
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117597, Singapore.
Ee Ling
EL
Ng
Ya
Y
Wang
Bor Luen
BL
Tang
D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D021381:Protein Transport / Q000502:physiology*; D011817:Rabbits; D051381:Rats; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D021601:trans-Golgi Network / Q000502:physiology*
D000906:Antibodies; C484191:RAB22A protein, human; C484190:RAB31 protein, human; D020691:rab GTP-Binding Proteins