Understanding EEA1's Role in Membrane Endosome Fusion

Thu, 07/28/2011 - 03:34

EEA1, or Early Endosome Antigen 1 is a Rab5 effector essential for early endocytic membrane fusion. The EEA1 antibody is used in membrane trafficking and chaperone studies, and as an endosome marker. We at Novus Biologicals have a comprehensive antibody catalog of EEA1 products.

A homodimeric endosomal trafficking protein which was originally identified as an autoantigen, EEA1 antibody studies have shown the protein has a C-terminal FYVE zinc finger domain, which interacts with PtdIns[3]P (phosphatidylinositol 3-phosphate) enriched membrane vesicles, playing a vital role in the docking and fusion of early endosomes and penetrating bilayers.

Immunocytochemistry/Immunofluorescence: EEA1 Antibody

In 2009, an EEA1 antibody study by researchers at the University of Colorado Denver School of Medicine showed that acidic conditions considerably increased the affinity for domain insertion into PtdIns3P-enriched early vesicle membranes. POPC/POPE/PtdIns(3)P vesicles bound to the FYVE domain of with a Kd of 49 nM at pH 6.0. At pH 8.0, the association was approximately 24 fold weaker. It is thought the decreased affinity was probably due to increased rate of dissociation of EEA1 from the bilayers. It was shown that lowering the pH enhanced RUFY1, Vps27p, Hrs and WDFY1 FYVE domain- interaction with the PtdIns(3)P of the vesicle membranes in vivo and in vitro, suggesting members of the FYVE finger family may be pH-dependent.

The results suggested PtdIns(3)P binding, and insertion of the domain into the vesicle membrane, was regulated by the adjacent His residues of the R(R/K)HHCRXCG motif. The electrostatic contacts and catalytic protonation state of the His residues stabilise the FYVE domain in its lipid-bound form, increasing membrane residence time and penetration. A mutation in either of the two residues nullifies this effect.

Researchers have recently discovered a new subpopulation of early endosomes having Rab5 effector activity but lacking EEA1 interaction.

Novus Biologicals offers many EEA1 reagents for your research needs including:

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