TI  - Identification of vascular endothelial growth factor determinants for
      binding <prot>KDR</prot> and <prot>FLT-1</prot> receptors. Generation of receptor-selective <prot>VEGF</prot>
      variants by site-directed mutagenesis.
PG  - 5638-46
AB  - <prot>Vascular endothelial growth factor</prot> (<prot>VEGF</prot>) expression in various cell types
      is induced by hypoxia and other stimuli.   <prot>VEGF</prot>   mediates endothelial cell
      proliferation, angiogenesis, vascular growth, and vascular permeability
      via the endothelial cell receptors,  <prot>kinase insert domain-containing
      receptor</prot> (<prot>KDR</prot>)/<prot>fetal liver kinase 1</prot> (<prot>Flk-1</prot>)  and  <prot>FLT-1</prot> . Alanine-scanning
      mutagenesis was used to identify a positively charged surface in  <prot>VEGF</prot>  that
      mediates binding to  <prot>KDR</prot>/<prot>Flk-1</prot> . Arg82, Lys84 and His86, located in a
      hairpin loop, were found to be critical for binding <prot>KDR</prot>/<prot>Flk-1</prot>, while
      negatively charged residues, Asp63, Glu64, and Glu67, were associated with
      <prot>FLT-1</prot> binding. A <prot>VEGF</prot> model based on <prot>PDGFb</prot> indicated these positively and
      negatively charged regions are distal in the monomer but are spatially
      close in the dimer. Mutations within the <prot>KDR</prot> site had minimal effect on
      <prot>FLT-1</prot> binding, and mutants deficient in <prot>FLT-1</prot> binding did not affect <prot>KDR</prot>
      binding. Endothelial cell mitogenesis was abolished in mutants lacking <prot>KDR</prot>
      affinity; however, <prot>FLT-1</prot> deficient mutants induced normal proliferation.
      These results suggest dual sets of determinants in the   <prot>VEGF</prot>   dimer that
      cross-link cell surface receptors, triggering endothelial cell growth and
      angiogenesis. Furthermore, this mutational analysis implicates <prot>KDR</prot>, but
      not <prot>FLT-1</prot>, in <prot>VEGF</prot> induction of endothelial cell proliferation.
AD  - Department of Cardiovascular Research, Genentech, Inc., South San
