The growth-regulatory protein HCRP1/hVps37A is a subunit of mammalian ESCRT-I and mediates receptor down-regulation.
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.
Mesh Terms:
Amino Acid Sequence, DNA-Binding Proteins, Down-Regulation, Endosomal Sorting Complexes Required for Transport, Endosomes, GTPase-Activating Proteins, Hela Cells, Humans, Lysosome-Associated Membrane Glycoproteins, Lysosomes, Membrane Glycoproteins, Molecular Sequence Data, Phosphoproteins, Protein Subunits, RNA, Small Interfering, Receptor, Epidermal Growth Factor, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Species Specificity, Transcription Factors, Two-Hybrid System Techniques, Vesicular Transport Proteins
Amino Acid Sequence, DNA-Binding Proteins, Down-Regulation, Endosomal Sorting Complexes Required for Transport, Endosomes, GTPase-Activating Proteins, Hela Cells, Humans, Lysosome-Associated Membrane Glycoproteins, Lysosomes, Membrane Glycoproteins, Molecular Sequence Data, Phosphoproteins, Protein Subunits, RNA, Small Interfering, Receptor, Epidermal Growth Factor, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Species Specificity, Transcription Factors, Two-Hybrid System Techniques, Vesicular Transport Proteins
Mol. Biol. Cell
Date: Sep. 01, 2004
PubMed ID: 15240819
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