Deletion of the kinase insert sequence of the platelet-derived growth factor beta-receptor affects receptor kinase activity and signal transduction

Mol Cell Biol. 1990 Feb;10(2):801-9. doi: 10.1128/mcb.10.2.801-809.1990.

Abstract

A characteristic feature of the platelet-derived growth factor (PDGF) beta-receptor is the presence of an insert sequence in the protein tyrosine kinase domain. A receptor mutant which lacks the entire insert of 98 amino acids was expressed in CHO cells, and its functional characteristics were compared with those of the wild-type receptor. The mutant receptor bound PDGF-BB with high affinity and mediated internalization and degradation of the ligand with efficiency similar to that of the wild-type receptor but did not transduce a mitogenic signal. It was found to display a decreased autophosphorylation after ligand stimulation and had a decreased ability to phosphorylate exogenous substrates; phosphofructokinase was not phosphorylated at all, whereas a peptide substrate was phosphorylated, albeit at a lower rate compared with phosphorylation by the wild-type receptor. Furthermore, the mutant receptor did not mediate actin reorganization but mediated an increase in c-fos expression. The data indicate that the insert in the kinase domain of the PDGF beta-receptor is important for the substrate specificity or catalytic efficiency of the kinase; the deletion of the insert interferes with the transduction of some, but not all, of the signals that arise after activation of the receptor.

MeSH terms

  • Animals
  • Cell Line
  • Chromosome Deletion*
  • Cloning, Molecular
  • DNA Transposable Elements*
  • Gene Expression
  • Genes*
  • Genetic Vectors
  • Humans
  • Kinetics
  • Mutation
  • Phosphorylation
  • Plasmids
  • Platelet-Derived Growth Factor / metabolism
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism
  • Protein-Tyrosine Kinases / genetics
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogenes
  • Receptors, Cell Surface / genetics*
  • Receptors, Platelet-Derived Growth Factor
  • Signal Transduction*
  • Transfection

Substances

  • DNA Transposable Elements
  • Platelet-Derived Growth Factor
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-fos
  • Receptors, Cell Surface
  • Protein Kinases
  • Protein-Tyrosine Kinases
  • Receptors, Platelet-Derived Growth Factor