Abstract
Arginine (Arg)-based endoplasmic reticulum (ER) localization signals are sorting motifs involved in the quality control of multimeric membrane proteins. They are distinct from other ER localization signals like the C-terminal di-lysine [-K(X)KXX] signal. The Pmp2p isoproteolipid, a type I yeast membrane protein, reports faithfully on the activity of sorting signals when fused to a tail containing either an Arg-based motif or a -KKXX signal. This reporter reveals that the Arg-based ER localization signals from mammalian Kir6.2 and GB1 proteins are functional in yeast. Thus, the machinery involved in recognition of Arg-based signals is evolutionarily conserved. Multimeric presentation of the Arg-based signal from Kir6.2 on Pmp2p results in forward transport, which requires 14-3-3 proteins encoded in yeast by BMH1 and BMH2 in two isoforms. Comparison of a strain without any 14-3-3 proteins (Deltabmh2) and the individual Deltabmh1 or Deltabmh2 shows that the role of 14-3-3 in the trafficking of this multimeric Pmp2p reporter is isoform-specific. Efficient forward transport requires the presence of Bmh1p. The specific role of Bmh1p is not due to differences in abundance or affinity between the isoforms. Our results imply that 14-3-3 proteins mediate forward transport by a mechanism distinct from simple masking of the Arg-based signal.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / metabolism*
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Adaptor Proteins, Signal Transducing
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Amino Acid Sequence
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Arginine / genetics
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Arginine / metabolism
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Endoplasmic Reticulum / metabolism
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Gene Deletion
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Gene Dosage
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Genes, Reporter / genetics
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Molecular Sequence Data
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism*
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Phenotype
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Potassium Channels, Inwardly Rectifying / metabolism
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Protein Binding
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Protein Isoforms / metabolism
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Protein Transport
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Proteolipids / chemistry
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Proteolipids / genetics
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Proteolipids / metabolism*
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Receptors, GABA / genetics
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Receptors, GABA / metabolism
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Signal Transduction
Substances
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14-3-3 Proteins
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Adaptor Proteins, Signal Transducing
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BMH1 protein, S cerevisiae
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BMH2 protein, S cerevisiae
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Kir6.2 channel
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Membrane Proteins
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Nerve Tissue Proteins
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PMP2 protein, S cerevisiae
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Potassium Channels, Inwardly Rectifying
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Protein Isoforms
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Protein Subunits
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Proteolipids
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Receptors, GABA
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Saccharomyces cerevisiae Proteins
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Arginine