Diphtheria toxin and Pseudomonas exotoxin A (PA toxin) inhibit protein synthesis by catalyzing covalent binding of the ADP-ribose moiety of NAD to elongation factor-2 (EF2). EF2 is required for the translocation step in protein synthesis, where peptidyl-tRNA is moved to the next codon on mRNA from the acceptor site on the ribosome at the expense of the energy provided by hydrolysis of GTP bound to EF2.
NCBI Summary:
This gene encodes a member of the GTP-binding translation elongation factor family. This protein is an essential factor for protein synthesis. It promotes the GTP-dependent translocation of the nascent protein chain from the A-site to the P-site of the ribosome. This protein is completely inactivated by EF-2 kinase phosporylation.
Rapp et al. (1989) and (1988) reported the complete sequence of the coding region of human elongation factor 2 (EF-2) by enzymatic amplification of cDNA from human ovarian granulosa cells.
Cellular localization
Cytoplasmic
Comment
Ovarian function
Luteinization
Comment
A cDNA clone, pHGR81, encoding 358 amino-acid residues of the C-terminal region of human elongation factor 2 (EF-2), was isolated from a human ovarian granulosa cell cDNA library by Rapp et al. The deduced amino-acid sequence of pHGR81, when compared with the known identical amino-acid sequences of hamster as well as rat EF-2 revealed a substitution of a glutamine by an alanine residue in the partially determined human sequence.
Expression regulated by
Prolactin
Comment
Albarracin et al. (1994) reported a MW 100,000 phosphoprotein in the corpus luteum identified as elongation factor 2 (EF-2). Since prolactin (PRL) is necessary for optimal luteal development and protein synthesis, the authors determined whether this hormone affects the content and/or phosphorylation of EF-2 in the corpus luteum. PRL treatment enhanced the Ca2+/calmodulin (CaM)-dependent phosphorylation of endogenous EF-2 in luteal cytoplasmic extracts. Immunoblot analysis revealed that PRL had no effect on EF-2 levels, but examination of luteal EF-2 by two-dimensional isoelectric focusing/SDS-polyacrylamide gel electrophoresis showed that PRL increased the relative amount of the most basic dephosphorylated forms of EF-2. This
suggests that PRL induces net dephosphorylation of the protein in vivo.