title: An RBCC protein implicated in maintenance of steady-state neuregulin receptor levels.
abstract: Despite numerous recent advances in our understanding of the molecular mechanisms underlying receptor tyrosine kinase down-regulation and degradation in response to growth factor binding, relatively little is known about ligand-independent receptor tyrosine kinase degradation mechanisms. In a screen for proteins that might regulate the trafficking or localization of the ErbB3 receptor, we have identified a tripartite or RBCC (RING, B-box, coiled-coil) protein that interacts with the cytoplasmic tail of the receptor in an activation-independent manner. We have named this protein Nrdp1 for neuregulin receptor degradation protein-1. Northern blotting reveals ubiquitous distribution of Nrdp1 in human adult tissues, but message is particularly prominent in heart, brain, and skeletal muscle. Nrdp1 interacts specifically with the neuregulin receptors ErbB3 and ErbB4 and not with epidermal growth factor receptor or ErbB2. When coexpressed in COS7 cells, Nrdp1 mediates the redistribution of ErbB3 from the cell surface to intracellular compartments and induces the suppression of ErbB3 and ErbB4 receptor levels but not epidermal growth factor receptor or ErbB2 levels. A putative dominant-negative form of Nrdp1 potentiates neuregulin-stimulated Erk1/2 activity in transfected MCF7 breast tumor cells. Our observations suggest that Nrdp1 may act to regulate steady-state cell surface neuregulin receptor levels, thereby influencing the efficiency of neuregulin signaling.
authors.affiliation: Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
authors.forename: A John
authors.initials: AJ
authors.lastname: Diamonti
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Guy
authors.forename: Caryn
authors.initials: C
authors.lastname: Ivanof
authors.forename: Karen
authors.initials: K
authors.lastname: Wong
authors.forename: Colleen
authors.initials: C
authors.lastname: Sweeney
authors.forename: Kermit L
authors.initials: KL
authors.lastname: Carraway
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002417:Cattle; D002460:Cell Line; D002522:Chlorocebus aethiops; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D020880:Neuregulins / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D066247:Receptor, ErbB-4; D015398:Signal Transduction; D018411:Spodoptera / Q000166:cytology; D044767:Ubiquitin-Protein Ligases
chemical_list: D066246:ErbB Receptors; D020880:Neuregulins; D011506:Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D044767:Ubiquitin-Protein Ligases; C452580:RNF41 protein, human; C587689:ERBB4 protein, human