A multimeric membrane protein reveals 14-3-3 isoform specificity in forward transport in yeast

TY - JOUR

T1 - A multimeric membrane protein reveals 14-3-3 isoform specificity in forward transport in yeast

AU - Michelsen, Kai

AU - Mrowiec, Thomas

AU - Duderstadt, Karl E

AU - Frey, Steffen

AU - Minor, Daniel L

AU - Mayer, Matthias P

AU - Schwappach, Blanche

PY - 2006/7

Y1 - 2006/7

N2 - 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.

AB - 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.

KW - 14-3-3 Proteins/metabolism

KW - Adaptor Proteins, Signal Transducing

KW - Amino Acid Sequence

KW - Arginine/genetics

KW - Endoplasmic Reticulum/metabolism

KW - Gene Deletion

KW - Gene Dosage

KW - Genes, Reporter/genetics

KW - Membrane Proteins/chemistry

KW - Molecular Sequence Data

KW - Nerve Tissue Proteins/chemistry

KW - Phenotype

KW - Potassium Channels, Inwardly Rectifying/metabolism

KW - Protein Binding

KW - Protein Isoforms/metabolism

KW - Protein Subunits/genetics

KW - Protein Transport

KW - Proteolipids/chemistry

KW - Receptors, GABA/genetics

KW - Saccharomyces cerevisiae/chemistry

KW - Saccharomyces cerevisiae Proteins/chemistry

KW - Signal Transduction

U2 - 10.1111/j.1600-0854.2006.00430.x

DO - 10.1111/j.1600-0854.2006.00430.x

M3 - SCORING: Journal article

C2 - 16734667

VL - 7

SP - 903

EP - 916

JO - TRAFFIC

JF - TRAFFIC

SN - 1398-9219

IS - 7

ER -