Ligand-induced endocytosis of epidermal growth factor receptors that are defective in binding adaptor proteins.
Ligand-activated epidermal growth factor receptors (EGFRs) associate with coated pit adaptor proteins (AP2) in vivo, implying a mechanism for receptor retention in coated pits during internalization. Using an in vitro binding assay, we localized the adaptor binding determinant to residues 970-991 of EGFRs and confirmed specificity by competition with a synthetic peptide corresponding to this sequence. A mutant EGFR lacking this AP2 binding determinant did not associate with AP2 in vivo but demonstrated internalization and down-regulation kinetics indistinguishable from its wild-type counterpart. Immunocytochemistry confirmed ligand-induced internalization of the mutant EGFR. These data suggest that endocytic determinants are distinct from AP2 binding determinants and that processes other than association with AP2 regulate endocytosis of EGFRs.
Nesterov
A
A
Department of Medicine, University of California, San Diego School of Medicine, La Jolla 92093, USA.
Wiley
H S
HS
Gill
G N
GN
D033962:Adaptor Protein Complex 2; D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D001665:Binding Sites; D001692:Biological Transport; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D004705:Endocytosis; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D007150:Immunohistochemistry; D008024:Ligands; D008565:Membrane Proteins / Q000172:deficiency*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
D033962:Adaptor Protein Complex 2; D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D008024:Ligands; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors