TI  -  <prot>B61</prot>  is a ligand for the  <prot><prot>ECK</prot> receptor protein-tyrosine kinase</prot> .
PG  - 558-60
AB  - A protein ligand for the <prot><prot>ECK</prot> receptor protein-tyrosine kinase</prot> has been
      isolated by using the extracellular domain (<prot>ECK</prot>-X) of the receptor as an
      affinity reagent. Initially, concentrated cell culture supernatants were
      screened for receptor binding activity using immobilized <prot>ECK</prot>-X in a
      surface plasmon resonance detection system. Subsequently, supernatants
      from selected cell lines were fractionated directly by receptor affinity
      chromatography, resulting in the single-step purification of <prot>B61</prot>, a
      protein previously identified as the product of an early response gene
      induced by <prot>tumour necrosis factor-alpha</prot>. We report here that recombinant
       <prot>B61</prot>  induces autophosphorylation of  <prot>ECK</prot>  in intact cells, consistent with
       <prot>B61</prot>  being an authentic ligand for  <prot>ECK</prot> . <prot>ECK</prot> is a member of a large orphan
      receptor protein-tyrosine kinase family headed by EPH, and we suggest that
      ligands for other members of this family will be related to <prot>B61</prot>, and can
      be isolated in the same way.
AD  - Amgen Inc., Thousand Oaks, California 91320-1789.
