title: Characterization of elk, a brain-specific receptor tyrosine kinase.
abstract: The elk gene encodes a novel receptorlike protein-tyrosine kinase, which belongs to the eph subfamily. We have previously identified a partial cDNA encompassing the elk catalytic domain (K. Letwin, S.-P. Yee, and T. Pawson, Oncogene 3:621-678, 1988). Using this cDNA as a probe, we have isolated cDNAs spanning the entire rat elk coding sequence. The predicted Elk protein contains all the hallmarks of a receptor tyrosine kinase, including an N-terminal signal sequence, a cysteine-rich extracellular domain, a membrane-spanning segment, a cytoplasmic tyrosine kinase domain, and a C-terminal tail. In both amino acid sequence and overall structure, Elk is most similar to the Eph and Eck protein-tyrosine kinases, suggesting that the eph, elk, and eck genes encode members of a new subfamily of receptorlike tyrosine kinases. Among rat tissues, elk expression appears restricted to brain and testes, with the brain having higher levels of both elk RNA and protein. Elk protein immunoprecipitated from a rat brain lysate becomes phosphorylated on tyrosine in an in vitro kinase reaction, consistent with the prediction that the mammalian elk gene encodes a tyrosine kinase capable of autophosphorylation. The characteristics of the Elk tyrosine kinase suggest that it may be involved in cell-cell interactions in the nervous system.
authors.affiliation: Division of Molecular and Developmental Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Lhoták
authors.forename: P
authors.initials: P
authors.lastname: Greer
authors.forename: K
authors.initials: K
authors.lastname: Letwin
authors.forename: T
authors.initials: T
authors.lastname: Pawson
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000936:Antigen-Antibody Complex / Q000032:analysis; D001483:Base Sequence; D001921:Brain / Q000201:enzymology*; D015342:DNA Probes; D004268:DNA-Binding Proteins; D015723:Gene Library; D007118:Immunoassay; D008969:Molecular Sequence Data; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D011518:Proto-Oncogene Proteins; D051381:Rats; D011916:Rats, Inbred F344; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D036224:Receptor, EphB4; D036081:Receptors, Eph Family; D015183:Restriction Mapping; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1
chemical_list: D000596:Amino Acids; D000936:Antigen-Antibody Complex; D015342:DNA Probes; D004268:DNA-Binding Proteins; C494114:Elk1 protein, rat; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D036224:Receptor, EphB4; D036081:Receptors, Eph Family