title: Identification, molecular cloning, and characterization of dual leucine zipper bearing kinase. A novel serine/threonine protein kinase that defines a second subfamily of mixed lineage kinases.
abstract: Molecular cloning using a degenerate oligonucleotide-based polymerase chain reaction was undertaken to test the possibility that novel, developmentally regulated protein kinases are expressed in the embryonic mouse kidney. Several receptor tyrosine kinase and serine/threonine kinase cDNA clones were identified. One of these, designated DLK, represented a novel gene product whose 3.6-kilobase transcript was expressed in a tissue-specific and developmentally regulated fashion. Several clones encoding the entire open reading frame were isolated and sequenced. The identified open reading frame encodes an 888-amino acid polypeptide that defines a new subfamily within the mixed lineage protein kinase family. Sequence analysis revealed: 1) a kinase catalytic domain most characteristic of serine/threonine kinases but hybrid between members of the family of microtubule-associated protein kinase kinase kinases and the fibroblast growth factor receptor family; 2) two putative alpha-helical leucine zipper motifs separated by a 25-amino acid charged intermediate segment but lacking an NH2-terminal basic domain; and 3) COOH-terminal and NH2-terminal proline-rich domains suggestive of src homology 3 (SH3) domain binding regions. Rabbit polyclonal immune sera generated against a carboxyl-terminal bacterial fusion protein recognized a protein with an apparent molecular mass of 130 kDa in COS 7 cells that were transiently transfected with a full-length DLK cDNA expression vector. Moreover, COS 7 cells transiently transfected with an epitope-tagged DLK expression vector expressed protein with an apparent molecular mass of 130 kDa that became autophosphorylated on serine and threonine in an in vitro kinase assay.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109-0676.
authors.forename: L B
authors.initials: LB
authors.lastname: Holzman
authors.forename: S E
authors.initials: SE
authors.lastname: Merritt
authors.forename: G
authors.initials: G
authors.lastname: Fan
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D007668:Kidney / Q000196:embryology / Q000201:enzymology; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D018076:DNA, Complementary; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C090757:mitogen-activated protein kinase kinase kinase 12