Isolation and characterization of human casein kinase I epsilon (CKI), a novel member of the CKI gene family.

Published

Journal Article

The casein kinase I (CKI) gene family is a rapidly enlarging group whose members have been implicated in the control of cytoplasmic and nuclear processes, including DNA replication and repair. We report here the cloning and characterization of a novel isoform of CKI from a human placental cDNA library. The cDNA for this isoform, hCKI epsilon, predicts a basic polypeptide of 416 amino acids and a molecular mass of 47.3 kDa. It encodes a core kinase domain of 285 amino acids and a carboxyl-terminal tail of 123 amino acids. The kinase domain is 53-98% identical to the kinase domains of other CKI family members and is most closely related to the delta isoform. Localization of the hCKI epsilon gene to chromosome 22q12-13 and the hCKI delta gene to chromosome 17q25 confirms that these are distinct genes in the CKI family. Northern blot analysis shows that hCKI epsilon is expressed in multiple human cell lines. Recombinant hCKI epsilon is an active enzyme that phosphorylates known CKI substrates including a CKI-specific peptide substrate and is inhibited by CKI-7, a CKI-specific inhibitor. A budding yeast isoform of CKI, HRR25, has been implicated in DNA repair responses. Expression of hCKI epsilon but not hCKI alpha rescued the slow-growth phenotype of a Saccharomyces cerevisiae strain with a deletion of HRR25. Human CKI epsilon is a novel CKI isoform with properties that overlap those of previously described CKI isoforms.

Full Text

Duke Authors

Cited Authors

  • Fish, KJ; Cegielska, A; Getman, ME; Landes, GM; Virshup, DM

Published Date

  • June 23, 1995

Published In

Volume / Issue

  • 270 / 25

Start / End Page

  • 14875 - 14883

PubMed ID

  • 7797465

Pubmed Central ID

  • 7797465

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.270.25.14875

Language

  • eng

Conference Location

  • United States