EEF2K (Ser-445), Phosphospecific Antibody

Eukaryotic elongation factor 2 (eEF2) catalyzes the translocation of peptidyl-tRNA from the A site to the P site on the ribosome. eEF2 kinase (eEF2K) phosphorylates and inactivates eEF2, resulting in the inhibition of peptide-chain elongation. eEF2K is normally dependent on Ca2+ ions and calmodulin, and can be activated by PKA in response to elevated cAMP levels during cell stress- or starvation-related conditions. Regulation of eEF2K occurs through phosphorylation at multiple sites. Ser-78 phosphorylation is required for calmodulin binding and eEF2K activity, while phosphorylation of Ser-500 is required for Ca2+/calmodulin-independent kinase activity. Thr-348 is an autophosphorylation site that is required for kinase activity. Inhibitory phosphorylation may also regulate eEF2K, since phosphorylation at Ser-359 by SAPK4/p38δ causes inactivation of eEF2K. Thus, multisite phospho-regulation of eEF2K may be important for proper control of eEF2K activity and protein translation.

The antibody was cross-absorbed to unphosphorylated eEF2K (Ser-445) before affinity purification using phospho-eEF2K (Ser-445) peptide (without carrier) . This antibody detects a 105 kDa* protein corresponding to the molecular mass of eEF2K on SDS-PAGE immunoblots of Jurkat cells treated with Calyculin A, and this reactivity is removed after lambda phosphatase treatment. This sequence is well conserved in rat, mouse, and fish eEF2K, and has low homology to other proteins.