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| Subject Categories: Membranes & Transport |
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| The EMBO Journal
(2002) 21, 6105–6113, doi: 10.1093/emboj/cdf605 |
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| Cargo selection into COPII vesicles is driven by the Sec24p subunit |
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| Elizabeth Miller1, Bruno Antonny1, 2, Susan Hamamoto1, 3 and Randy Schekman1, 3 |
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1 Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA 2 Present address: IPMC-CNRS, 660 Route des Lucioles, 06560 Valbonne, France 3 Howard Hughes Medical Institute, University of California, Berkeley, CA 94720-3202, USA To whom correspondence should be addressed Randy Schekman, schekman@uclink4.berkeley.edu Received 16 July 2002; Revised 21 September 2002; Accepted 23 September 2002. |
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| Abstract |
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| Transport of secretory proteins out of the endoplasmic reticulum (ER) is mediated by vesicles generated by the COPII coat complex. In order to understand how cargo molecules are selected by this cytoplasmic coat, we investigated the functional role of the Sec24p homolog, Lst1p. We show that Lst1p can function as a COPII subunit independently of Sec24p on native ER membranes and on synthetic liposomes. However, vesicles generated with Lst1p in the absence of Sec24p are deficient in a distinct subset of cargo molecules, including the SNAREs, Bet1p, Bos1p and Sec22p. Consistent with the absence of any SNAREs, these vesicles are unable to fuse with Golgi membranes. Furthermore, unlike Sec24p, Lst1p fails to bind to Bet1p in vitro, indicating a direct correlation between cargo binding and recruitment into vesicles. Our data suggest that the principle role of Sec24p is to discriminate cargo molecules for incorporation into COPII vesicles. |
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| Keywords: cargo packaging, COPII, ER, transport vesicle, yeast |
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