The HECT domain ligase itch ubiquitinates endophilin and localizes to the trans-Golgi network and endosomal system.
Endophilin A1 is an SH3 domain-containing protein functioning in membrane trafficking on the endocytic pathway. We have identified the E3 ubiquitin ligase itch/AIP4 as an endophilin A1-binding partner. Itch belongs to the Nedd4/Rsp5p family of proteins and contains an N-terminal C2 domain, four WW domains and a catalytic HECT domain. Unlike other Nedd4/Rsp5p family members, itch possesses a short proline-rich domain that mediates its binding to the SH3 domain of endophilin A1. Itch ubiquitinates endophilin A1 and the SH3/proline-rich domain interaction facilitates this activity. Interestingly, itch co-localizes with markers of the endosomal system in a C2 domain-dependent manner and upon EGF stimulation, endophilin A1 translocates to an EGF-positive endosomal compartment where it colocalizes with itch. Moreover, EGF treatment of cells stimulates endophilin A1 ubiquitination. We have thus identified endophilin A1 as a substrate for the endosome-localized ubiquitin ligase itch. This interaction may be involved in ubiquitin-mediated sorting mechanisms operating at the level of endosomes.
Angers
Annie
A
Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, 3801 University St., Montréal, Quebec H3A 2B4, Canada. Annie.Angers@umontreal.ca
Ramjaun
Antoine R
AR
McPherson
Peter S
PS
D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D017931:DNA Primers; D011992:Endosomes / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D017931:DNA Primers; D012097:Repressor Proteins; D025801:Ubiquitin; D000217:Acyltransferases; C018764:2-acylglycerophosphate acyltransferase; C432966:ITCH protein, human; D044767:Ubiquitin-Protein Ligases