Relationships between EGFR signaling-competent and endocytosis-competent membrane microdomains.
Membrane microdomains, the so-called lipid rafts, function as platforms to concentrate receptors and assemble the signal transduction machinery. Internalization, in most cases, is carried out by different specialized structures, the clathrin-coated pits. Here, we show that several endocytic proteins are efficiently recruited to morphologically identified plasma membrane lipid rafts, upon activation of the epidermal growth factor (EGF) receptor (EGFR), a receptor tyrosine kinase. Analysis of detergent-resistant membrane fractions revealed that the EGF-dependent association of endocytic proteins with rafts is as efficient as that of signaling effector molecules, such as Grb2 or Shc. Finally, the EGFR, but not the nonsignaling transferrin receptor, could be localized in nascent coated pits that almost invariably contained raft membranes. Thus, specialized membrane microdomains have the ability to assemble both the molecular machineries necessary for intracellular propagation of EGFR effector signals and for receptor internalization.
Puri
Claudia
C
MicroScoBio Research Center, Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy.
Tosoni
Daniela
D
Comai
Riccardo
R
Rabellino
Andrea
A
Segat
Daniela
D
Caneva
Federico
F
Luzzi
Paola
P
Di Fiore
Pier Paolo
PP
Tacchetti
Carlo
C
D018929:Cell Culture Techniques; D002784:Cholesterol / Q000032:analysis; D022163:Clathrin-Coated Vesicles / Q000378:metabolism / Q000648:ultrastructure; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism / Q000648:ultrastructure; D016895:Culture Media, Serum-Free; D004705:Endocytosis / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D011485:Protein Binding; D015398:Signal Transduction; D013696:Temperature; D013997:Time Factors; D047392:beta-Cyclodextrins / Q000494:pharmacology
D016895:Culture Media, Serum-Free; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D004815:Epidermal Growth Factor; D002784:Cholesterol; D066246:ErbB Receptors