Abstract
Apg8 is a ubiquitin-like protein involved in autophagy in yeast. Apg8 is covalently but transiently attached to membrane lipids through the actions of activating, conjugating, and processing/deconjugating enzymes. The mammalian Apg8 homologues GATE-16, GARARAP, and MAP1-LC3 have been implicated in intra-Golgi transport, receptor sorting, and autophagy, respectively. All are served by a single set of activating and conjugating enzymes. Here we identify a novel mammalian Apg8 homologue, which we name Apg8L, and describe the synthesis of electrophilic probes based on the GATE-16, GARARAP, MAP1-LC3, and Apg8L proteins. These probes not only form specific adducts in crude cell lysates, but also allow identification of the cellular proteases specific for the C termini of these Apg8 homologues. We find a single protease, Apg4B/autophagin-1, capable of acting on GATE-16, GABARAP, MAP1-LC3, and Apg8L. The Apg4B/autophagin-1 protease thus serves as a processing/deconjugating enzyme for these four highly divergent mammalian Apg8 homologues.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Apoptosis Regulatory Proteins
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Autophagy
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Autophagy-Related Protein 8 Family
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Autophagy-Related Proteins
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Carrier Proteins / metabolism*
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Cysteine Endopeptidases
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Cytoskeletal Proteins*
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Exopeptidases / metabolism*
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins / metabolism
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Mice
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Microtubule-Associated Proteins / metabolism
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Molecular Probes / chemical synthesis
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Protein Processing, Post-Translational
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Saccharomyces cerevisiae Proteins*
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Sequence Alignment
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Sequence Homology
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Ubiquitins / metabolism
Substances
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ATG8 protein, S cerevisiae
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Apoptosis Regulatory Proteins
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Autophagy-Related Protein 8 Family
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Autophagy-Related Proteins
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Carrier Proteins
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Cytoskeletal Proteins
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GABARAP protein, mouse
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Gabarapl1 protein, mouse
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Gabarapl2 protein, mouse
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Intracellular Signaling Peptides and Proteins
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Map1lc3b protein, mouse
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Membrane Proteins
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Microtubule-Associated Proteins
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Molecular Probes
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Saccharomyces cerevisiae Proteins
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Ubiquitins
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Exopeptidases
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Atg4b protein, mouse
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Cysteine Endopeptidases