Abstract
We have identified and characterized a Microtubule Interacting and Transport (MIT) domain at the N terminus of the deubiquitinating enzyme UBPY/USP8. In common with other MIT-containing proteins such as AMSH and VPS4, UBPY can interact with CHMP proteins, which are known to regulate endosomal sorting of ubiquitinated receptors. Comparison of binding preferences for the 11 members of the human CHMP family between the UBPY MIT domain and another ubiquitin isopeptidase, AMSH, reveals common interactions with CHMP1A and CHMP1B but a distinct selectivity of AMSH for CHMP3/VPS24, a core subunit of the ESCRT-III complex, and UBPY for CHMP7. We also show that in common with AMSH, UBPY deubiquitinating enzyme activity can be stimulated by STAM but is unresponsive to its cognate CHMPs. The UBPY MIT domain is dispensable for its catalytic activity but is essential for its localization to endosomes. This is functionally significant as an MIT-deleted UBPY mutant is unable to rescue its binding partner STAM from proteasomal degradation or reverse a block to epidermal growth factor receptor degradation imposed by small interfering RNA-mediated depletion of UBPY.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence / genetics
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Endopeptidases / genetics
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Endopeptidases / metabolism*
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Endosomal Sorting Complexes Required for Transport
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Endosomes / metabolism*
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ErbB Receptors / genetics
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ErbB Receptors / metabolism*
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HeLa Cells
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Humans
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Multiprotein Complexes / genetics
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Multiprotein Complexes / metabolism
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism*
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Proteasome Endopeptidase Complex / genetics
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Proteasome Endopeptidase Complex / metabolism
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Protein Binding / physiology
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Protein Structure, Tertiary / physiology
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Protein Transport / physiology
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RNA, Small Interfering / genetics
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Sequence Deletion
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Ubiquitin Thiolesterase / genetics
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Ubiquitin Thiolesterase / metabolism
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Ubiquitination / physiology
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Vesicular Transport Proteins / genetics
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Vesicular Transport Proteins / metabolism*
Substances
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CHMP1A protein, human
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CHMP1B protein, human
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CHMP3 protein, human
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CHMP7 protein, human
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Endosomal Sorting Complexes Required for Transport
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Multiprotein Complexes
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Nerve Tissue Proteins
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Nuclear Proteins
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RNA, Small Interfering
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STAMBP protein, human
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Vesicular Transport Proteins
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ErbB Receptors
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Endopeptidases
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USP8 protein, human
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Ubiquitin Thiolesterase
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Proteasome Endopeptidase Complex
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ubiquitin isopeptidase