Detection of anti-elongation factor 2 kinase (calmodulin-dependent protein kinase III) antibodies in patients with systemic lupus erythematosus.
Elongation factor 2 kinase (eEF-2K), also known as calmodulin-dependent protein kinase III, is a member of the calmodulin-mediated signaling pathway that links activation of cell surface receptors to cell division. The activity of eEF-2K is increased in many human cancers and may be a valid target for anti-cancer treatment. It is one of the unconventional eukaryotic protein kinases with respect to its structural domains in comparison to other members of the serine/threonine protein kinase superfamily. eEF-2K is highly conserved in nature. For example, the amino acid sequence of human eEF-2K is 90% identical to mouse and rat eEF-2Ks and 40% identical to that of the C. elegans enzyme. Therefore it has been difficult to generate high-titer and high-specificity antibodies to the human enzyme by traditional techniques. Patients with systemic lupus erythematosus (SLE) produce auto-antibodies to a variety of cellular proteins, including members of the protein translation apparatus. Hence, we developed an ELISA assay that could detect anti-eEF2K antibodies from sera of SLE patients using purified eEF-2K as an antigen. We screened 117 sera from SLE patients. High-titer anti-eEF-2K antibodies were detected in 72 subjects. One of the high-titer sera was used for further characterization. The auto-antibody recognized eEF-2K on immunoblots and immunoprecipitated the kinase with intact enzyme activity. In conclusion, anti-eEF-2K antibodies are found in sera of SLE patients and are useful tools to study the role of this highly conserved enzyme.
Arora
Sonia
S
Department of Medicine, The Cancer Institute of New Jersey, UMDNJ-Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA.
Yang
Jin-Ming
JM
Craft
Joseph
J
Hait
William
W
D000818:Animals; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000276:immunology* / Q000378:metabolism; D054736:Elongation Factor 2 Kinase; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D011233:Precipitin Tests; D051381:Rats; D014407:Tumor Cells, Cultured
D001323:Autoantibodies; C517689:EEF2K protein, human; C517691:Eef2k protein, rat; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517690:Eef2k protein, mouse; D054736:Elongation Factor 2 Kinase