title: Intracellular expression of the truncated extracellular domain of c-erbB-3/HER3.
abstract: The ERBB3 gene is expressed as a 6.2- and a 1.4-kb transcript. The former encodes the full-length transmembrane protein and the latter a truncated extracellular fragment consisting of 140 amino acids of the c-erbB-3 protein followed by 43 unique residues. We have examined the expression of the two ERBB3 transcripts by Northern blotting in cancer cell lines and normal human fetal and adult tissues. We expressed the truncated receptor fragment and showed that it was glycosylated, probably with a single N-linked complex sugar chain, and that the protein was a 58-kDa disulphide-linked dimer. We were able to crosslink iodinated neuregulin (NRG)-1beta to the full-length solubilised receptor but not to the truncated dimeric protein. Using Western blot analysis, the truncated protein was shown to be present in cell lysates and, using immunoelectron microscopy, in vesicular structures within cells and associated with the plasma cell membrane.
authors.affiliation: Department of Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: R
authors.initials: R
authors.lastname: Srinivasan
authors.forename: K E
authors.initials: KE
authors.lastname: Leverton
authors.forename: H
authors.initials: H
authors.lastname: Sheldon
authors.forename: H C
authors.initials: HC
authors.lastname: Hurst
authors.forename: C
authors.initials: C
authors.lastname: Sarraf
authors.forename: W J
authors.initials: WJ
authors.lastname: Gullick
mesh_terms: D000818:Animals; D001943:Breast Neoplasms; D019556:COS Cells; D003001:Cloning, Molecular; D019281:Dimerization; D005091:Exons; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006031:Glycosylation; D006801:Humans; D007438:Introns; D008024:Ligands; D008113:Liver Neoplasms; D008297:Male; D016253:Microscopy, Immunoelectron; D010051:Ovarian Neoplasms; D011471:Prostatic Neoplasms; D017434:Protein Structure, Tertiary / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D020893:Receptor, ErbB-3 / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D013274:Stomach Neoplasms; D013440:Sulfides / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000502:physiology / Q000648:ultrastructure
chemical_list: D008024:Ligands; D012333:RNA, Messenger; D013440:Sulfides; D020893:Receptor, ErbB-3