Endocytosis of EGFR requires its kinase activity and N-terminal transmembrane dimerization motif.
EGFR signaling is attenuated by endocytosis and degradation of receptor-ligand complexes in lysosomes. Endocytosis of EGFR is known to be regulated by multiple post-translational modifications. The observation that prevention of these modifications does not block endocytosis completely, suggests the involvement of other mechanism(s). Recently, receptor clustering has been suggested to induce internalization of multiple types of membrane receptors. However, the mechanism of clustering-induced internalization remains unknown. We have used biparatopic antibody fragments from llama (VHHs) to induce EGFR clustering without stimulating tyrosine kinase activity. Using this approach, we have found an essential role for the N-terminal GG4-like dimerization motif in the transmembrane domain (TMD) for clustering-induced internalization. Moreover, conventional EGF-induced receptor internalization depends exclusively on this TMD dimerization and kinase activity. Mutations in this dimerization motif eventually lead to reduced EGFR degradation and sustained signaling. We propose a novel role for the TMD dimerization motif in the negative-feedback control of EGFR. The widely conserved nature of GG4-like dimerization motifs in transmembrane proteins suggests a general role for these motifs in clustering-induced internalization.
Cell Biology, Department of Biology, Science Faculty, Utrecht University, 3584 CH Utrecht, The Netherlands.
Raimond
R
Heukers
Jeroen F
JF
Vermeulen
Farzad
F
Fereidouni
Arjen N
AN
Bader
Jarno
J
Voortman
Rob C
RC
Roovers
Hans C
HC
Gerritsen
Paul M P
PM
van Bergen En Henegouwen
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004705:Endocytosis; D066246:ErbB Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
D066246:ErbB Receptors
Clustering; EGFR endocytosis; Nanobody; Transmembrane domain; VHH