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

Kai Michelsen, Thomas Mrowiec, Karl E. Duderstadt, Steffen Frey, Daniel L. Minor, Matthias P. Mayer, Blanche Schwappach

    Research output: Contribution to journalArticlepeer-review


    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 (Δbmh1Δbmh2) and the individual Δbmh1 or Δbmh2 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. © Blackwell Munksgaard, 2006.
    Original languageEnglish
    Pages (from-to)903-916
    Number of pages13
    JournalTraffic (Malden): the international journal of intracellular transport
    Issue number7
    Publication statusPublished - Jul 2006


    • 14-3-3 proteins
    • Arg-based ER localization signal
    • Forward transport
    • Multimeric membrane protein
    • Yeast


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