title: The growth-regulatory protein HCRP1/hVps37A is a subunit of mammalian ESCRT-I and mediates receptor down-regulation.
abstract: The biogenesis of multivesicular bodies and endosomal sorting of membrane cargo are driven forward by the endosomal sorting complexes required for transport, ESCRT-I, -II, and -III. ESCRT-I is characterized in yeast as a complex consisting of Vps23, Vps28, and Vps37. Whereas mammalian homologues of Vps23 and Vps28 (named Tsg101 and hVps28, respectively) have been identified and characterized, a mammalian counterpart of Vps37 has not yet been identified. Here, we show that a regulator of proliferation, hepatocellular carcinoma related protein 1 (HCRP1), interacts with Tsg101, hVps28, and their upstream regulator Hrs. The ability of HCRP1 (which we assign the alternative name hVps37A) to interact with Tsg101 is conferred by its mod(r) domain and is shared with hVps37B and hVps37C, two other mod(r) domain-containing proteins. HCRP1 cofractionates with Tsg101 and hVps28 by size exclusion chromatography and colocalizes with hVps28 on LAMP1-positive endosomes. Whereas depletion of Tsg101 by siRNA reduces cellular levels of both hVps28 and HCRP1, depletion of HCRP1 has no effect on Tsg101 or hVps28. Nevertheless, HCRP1 depletion strongly retards epidermal growth factor (EGF) receptor degradation. Together, these results indicate that HCRP1 is a subunit of mammalian ESCRT-I and that its function is essential for lysosomal sorting of EGF receptors.
authors.affiliation: Department of Biochemistry, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway.
authors.forename: Kristi G
authors.initials: KG
authors.lastname: Bache
authors.forename: Thomas
authors.initials: T
authors.lastname: Slagsvold
authors.forename: Alicia
authors.initials: A
authors.lastname: Cabezas
authors.forename: Ken R
authors.initials: KR
authors.lastname: Rosendal
authors.forename: Camilla
authors.initials: C
authors.lastname: Raiborg
authors.forename: Harald
authors.initials: H
authors.lastname: Stenmark
mesh_terms: D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism; D021122:Protein Subunits; D034741:RNA, Small Interfering / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000099177:Tsg101 Protein; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D066246:ErbB Receptors; D020690:GTPase-Activating Proteins; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D010750:Phosphoproteins; D021122:Protein Subunits; D034741:RNA, Small Interfering; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D033921:Vesicular Transport Proteins; D000099177:Tsg101 Protein; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C115245:SRN2 protein, S cerevisiae; C476409:VPS28 protein, human; C496437:VPS37A protein, human; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate