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Like
other components of the translation machinery (EF-1a
and EF1b),
EF-2 is an actin binding protein. An interaction was first indicated by
immunofluorescence co-localisation of EF-2 with F-actin in fibroblasts (Shestokova,
et al, 1991,1993a, b), and
later confirmed by co-sedimentation assay (Bektas
et al, 1994).
Binding of EF-2 was reported to be increased two-fold (Fig.1 in Bektas
et al,
1994 although elsewhere in the paper the authors claim 4 fold?) in the presence
of GTPgS.
Binding to F-actin had a Kd of 0.85mM
(micromolar) and was inhibited by G-actin indicating that EF-2 also binds
G-actin. Competition between EF-2 and EF-1a
was observed. EF-2 may
bind actin through sub-domain 2 as EF-2 competes with DNAse1 for binding (Bektas
et al, 1998).
Indirect effects are also possible as is the case for profilin. Diphtheria
toxin catalyses the transfer of an ADP-ribosyl group from NAD+ to EF-2 and
prevents protein synthesis, but this neither prevents EF-2 being localized to
F-actin in cells (Shestakova
et al, 1993) or
affect F-actin binding in vitro (Bektas
et al, 1994).
References:-
Bektas,
M., R. Nurten, et al. (1994). “Interactions of eukaryotic elongation factor 2
with actin: a possible link between protein synthetic machinery and
cytoskeleton.” FEBS letters
356, 89-93.
Bektas,
M., Nurten, R., Sayers, Z.
& Bermek, E. (1998).
“Interactions of elongation factor 2 with the cytoskeleton and interference
with DNase I binding to actin.” Eur.J.Biochem.
256, 142-147.
Shestakova,
E. A., Motuz, L. P., Minin, A. A., Gelfand, V. I. & Gavrilova, L. P. (1991)
Some of eukaryotic elongation factor 2 is localized with actin microfilament
bundles in mouse embryo fibroblasts. Cell Biol.Int.Rep. 15, 75-84.
Shestakova,
E. A., Motuz, L. P., Minin, A. A. & Gavrilova, L. P. (1993a) Study of
localization of the protein-synthesizing machinery along actin actin filament
bundles., Cell Biol.International. 17, 409-416.
Shestakova,
E. A., Motuz, L. P. & Gavrilova, L. P. (1993b) Co-localization of components
of the protein-synthesizing machinery with the cytoskeleton in G0-arrested
cells. Cell Biol.International. 17, 417-424.
Watanabe,
S., Sakurai, K., Amagai, A. & Maseda, Y. (2003) Unexpected roles of a Dictyostelium
homologue of eukaryotic EF-2 in growth and differentiation. J Cell Sci. 116,
2647-2654.
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