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A tyrosine residue in the juxtamembrane segment of the platelet-derived growth factor beta-receptor is critical for ligand-mediated endocytosis

Authors
Publication Date
Keywords
  • Vascular/*Metabolism Humans Iodine Radioisotopes Kinetics Molecular Sequence Data Mutagenesis
  • Amino Acid Sequence Animals Aorta Clone Cells *Endocytosis Endothelium
  • Igf Type 2/Chemistry Receptors
  • Site-Directed Platelet-Derived Growth Factor/*Metabolism Receptor
  • Platelet-Derived Growth Factor/Biosynthesis/Chemistry/*Metabolism Recombinant Proteins/Metabolism Se
  • Amino Acid Swine Transfection *Tyrosine
  • Medicine And Health Sciences
Disciplines
  • Biology

Abstract

The importance of tyrosine residues in ligand-mediated endocytosis of the platelet-derived growth factor beta-receptor was analyzed using a series of tyrosine residue-mutated beta-receptors, which together cover all of the tyrosine residues in the juxtamembrane segment, the kinase insert, and the carboxyl-terminal tail; also certain of the tyrosine residues within the first and second parts of the kinase domain were examined. Of all of these tyrosine residues, only Tyr-579 seemed to be important for internalization, since mutation of this residue resulted in substantial reduction in the rate of ligand-induced receptor internalization (approximately 60% of the wild-type level). Replacement of Tyr-579 by either an aromatic (Phe) or a nonaromatic (Asp) residue reduced the efficiency of the mutant receptors in internalization to the same extent, suggesting that the role of Tyr-579 in the beta-receptor is different from that of the previously described tyrosine-based internalization motifs, which were first determined for the low density lipoprotein receptor. Tyr-579 has been found to be an autophosphorylation site in the beta-receptor. Moreover, the internalization rate of a kinase negative receptor mutant was not altered by the additional mutation of Tyr-579. Thus, it is likely that phosphorylation of Tyr-579 is important for ligand-induced internalization of the beta-receptor.

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