Epsin 1 is involved in recruitment of ubiquitinated EGF receptors into clathrin-coated pits.
Epsin consists of an epsin NH(2)-terminal homology domain that promotes interaction with phospholipids, several AP-2-binding sites, two clathrin-binding sequences and several Eps15 homology domain-binding motifs. Epsin additionally possesses ubiquitin-interacting motifs (UIMs) and has been demonstrated to bind ubiquitinated cargo. We therefore investigated whether epsin promoted clathrin-mediated endocytosis of the ubiquitinated EGF receptor (EGFR). By immunoprecipitation, we found that epsin 1 interacted with ubiquitinated EGFR and that functional UIMs were essential for complex formation. Furthermore, RNA interference-mediated knockdown of epsin 1 was found to inhibit internalization of the EGFR, while having no effect on endocytosis of the transferrin receptor. Additionally, upon knockdown of epsin 1, translocation of the EGFR to central parts of clathrin-coated pits was inhibited. This supports the contention that epsin 1 promotes endocytosis of the ubiquitinated EGFR.
Kazazic
Maja
M
Institute of Pathology, University of Oslo, Rikshospitalet HF, N-0027 Oslo, Norway.
Bertelsen
Vibeke
V
Pedersen
Ketil Winther
KW
Vuong
Tram Thu
TT
Grandal
Michael Vibo
MV
Rødland
Marianne Skeie
MS
Traub
Linton M
LM
Stang
Espen
E
Madshus
Inger Helene
IH
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism*; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism* / Q000648:ultrastructure; D004705:Endocytosis; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D008854:Microscopy, Electron; D011485:Protein Binding; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics; D011990:Receptors, Transferrin / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*
D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; D025801:Ubiquitin; C114154:epsin; D066246:ErbB Receptors