Multiple cDNAs encoding the esk kinase predict transmembrane and intracellular enzyme isoforms

Elizabeth M.J. Douville, Daniel E.H. Afar, Brian W. Howell, Kenneth Letwin, Lisa Tannock, Yaacov Ben-David, Tony Pawson, John C. Bell

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


A novel protein kinase, the Esk kinase, has been isolated from an embryonal carcinoma (EC) cell line by using an expression cloning strategy. Sequence analysis of two independent cDNA clones (2.97 and 2.85 kb) suggested the presence of two Esk isoforms in EC cells. The esk-1 cDNA sequence predicted an 857-amino-acid protein kinase with a putative membrane-spanning domain, while the esk-2 cDNA predicted an 831-amino-acid kinase which lacked this domain. In adult mouse cells, esk mRNA levels were highest in tissues possessing a high proliferation rate or a sizeable stem cell compartment, suggesting that the Esk kinase may play some role in the control of cell proliferation or differentiation. As anticipated from the screening procedure, bacterial expression of the Esk kinase reacted with antiphosphotyrosine antibodies on immunoblots. Furthermore, in in vitro kinase assays, the Esk kinase was shown to phosphorylate both itself and the exogenous substrate myelin basic protein on serine, threonine, and tyrosine residues, confirming that the Esk kinase is a novel member of the serine/threonine/tyrosine family of protein kinases.

Original languageEnglish
Pages (from-to)2681-2689
Number of pages9
JournalMolecular and Cellular Biology
Issue number6
StatePublished - Jun 1992

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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