A complex peptide-sorting signal, but no mRNA signal, is required for the Sec-independent transport of Ist2 from the yeast ER to the plasma membrane.
The yeast integral plasma membrane protein Ist2 belongs to a group of membrane proteins which are synthesized from localized mRNAs. The protein reaches the plasma membrane via the ER on a route operating independently of the classical secretory pathway. We have identified a complex peptide-sorting signal located at the extreme C-terminus. This sorting signal operates independently of targeting information in IST2 mRNA and sorting to the plasma membrane does not require She-mediated mRNA transport into daughter cells. Based on these results, we suggest a posttranslational mechanism, which leads to the concentration of Ist2--via multimerization--at ER sites, followed by direct transport to the plasma membrane. This novel mechanism operates downstream of IST2 mRNA localization.
Franz
Anna
A
Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
Maass
Kiran
K
Seedorf
Matthias
M
D022181:COP-Coated Vesicles; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020690:GTPase-Activating Proteins; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D020690:GTPase-Activating Proteins; C477782:IST2 protein, S cerevisiae; D046912:Multiprotein Complexes; D021382:Protein Sorting Signals; D012331:RNA, Fungal; D012333:RNA, Messenger; D011994:Recombinant Proteins; C079037:SEC23 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins