Document Detail

The small GTPase Rab22 interacts with EEA1 and controls endosomal membrane trafficking.
MedLine Citation:
PMID:  11870209     Owner:  NLM     Status:  MEDLINE    
Rab22a is a small GTPase that is expressed ubiquitously in mammalian tissues and displays the highest sequence homology to Rab5. In BHK-21 cells, overexpression of the wild-type Rab22a caused formation of abnormally large vacuole-like structures containing the early-endosomal antigen EEA1 but not Rab11, a marker of recycling endosomes or the late-endosomal/lysosomal markers LAMP-1 and lyso-bis-phosphatidic acid. In HeLa cells, overexpressed Rab22a was found on smaller EEA1-positive endosomes, but a portion of the protein was also found in the Golgi complex. Using the yeast two-hybrid system and a biochemical pull-down assay, the GTP-bound form of Rab22a was found to interact with the N-terminus of EEA1. In HeLa cells overexpressing Rab22a or its mutants affected in the GTPase cycle, no significant changes were observed in the uptake of Alexa-transferrin. However, the GTPase-deficient Rab22a Q64L mutant caused a redistribution of transferrin-positive endosomes to the leading edges of cells and a fragmentation of the Golgi complex. In BHK cells, the Q64L mutant caused the accumulation of a fluid phase marker, TRITC-dextran, and a lysosomal hydrolase, aspartylglucosaminidase, in abnormal vacuole-like structures that contained both early and late endosome markers. Both the wild-type Rab22a and the Q64L mutant were found to interfere with the degradation of EGF. These results suggest that Rab22a may regulate the dynamic interactions of endosomal compartments and it may be involved in the communication between the biosynthetic and early endocytic pathways.
Maria Kauppi; Anne Simonsen; Bjørn Bremnes; Amandio Vieira; Judy Callaghan; Harald Stenmark; Vesa M Olkkonen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cell science     Volume:  115     ISSN:  0021-9533     ISO Abbreviation:  J. Cell. Sci.     Publication Date:  2002 Mar 
Date Detail:
Created Date:  2002-02-28     Completed Date:  2002-07-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0052457     Medline TA:  J Cell Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  899-911     Citation Subset:  IM    
Department of Molecular Medicine, National Public Health Institute (KTL), Biomedicum, PO Box 104, FIN-00251 Helsinki, Finland.
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MeSH Terms
Cell Compartmentation / physiology*
Cells, Cultured
Endocytosis / physiology*
Endosomes / metabolism*,  ultrastructure
Eukaryotic Cells / cytology,  enzymology*
Golgi Apparatus / metabolism,  ultrastructure
Intracellular Membranes / metabolism*
Membrane Proteins / metabolism*
Mutation / physiology
Protein Binding / physiology
Protein Isoforms / metabolism
Protein Transport / physiology*
Radioligand Assay
Recombinant Fusion Proteins / diagnostic use
Transferrin / genetics,  metabolism
Vesicular Transport Proteins
rab GTP-Binding Proteins / genetics,  metabolism*
rab5 GTP-Binding Proteins / genetics,  metabolism
Reg. No./Substance:
0/Membrane Proteins; 0/Protein Isoforms; 0/RAB22A protein, human; 0/Recombinant Fusion Proteins; 0/Vesicular Transport Proteins; 0/early endosome antigen 1; 11096-37-0/Transferrin; EC 3.6.1.-/rab GTP-Binding Proteins; EC GTP-Binding Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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