NOVEL PROTEIN-TYROSINE KINASE CDNAS RELATED TO FPS/FES AND EPH CLONED USING ANTI-PHOSPHOTYROSINE ANTIBODY

  • 1 December 1988
    • journal article
    • research article
    • Vol. 3  (6) , 621-627
Abstract
A rat brain .lambda.gt11 cDNA expression library was screened with anti-phosphotyrosine antibody to identify recombinant clones that encode enzymatically active protein-tyrosine kinases. The inserts of two bacteriophage that gave positive signals were sequenced. Both translation products possess sequence motifs characteristic of protein-tyrosine kinases. However, each polypeptide is distinct from previously described members of the tyrosine kinase family. The predicted product of the .lambda.B1 clone contains a catalytic domain and C-terminal tail most closely related to the eph gene product, a presumed transmembrane receptor-like protein-tyrosine kinase. The clone .lambda.B2 encodes a partial SH2 domain and a kinase domain similar in organization and sequence to the fps/fes cytoplasmic protein-tyrosine kinase. These new protein-tyrosine kinases (elk and flk) are apparently members of subfamilies for which eph and fps/fes are prototypes. elk is predominantly expressed in brain, while flk RNA is widely distributed and most abundant in testes. The preferential isolation of cDNAs for previously uncharacterized protein-tyrosine kinases in a screen based on catalytic activity suggests that additional members of the protein-tyrosine kinase family remain to be identified.