Endoplasmic reticulum localization of Sec12p is achieved by two mechanisms: Rer1p-dependent retrieval that requires the transmembrane domain and Rer1p-independent retention that involves the cytoplasmic domain.
Open Access
- 15 July 1996
- journal article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 134 (2), 279-293
- https://doi.org/10.1083/jcb.134.2.279
Abstract
Yeast Sec12p is a type II transmembrane protein in the ER, which is essential for the formation of transport vesicles. From biochemical and morphological lines of evidence, we have proposed that Sec12p is localized to the ER by two mechanisms: static retention in the ER and dynamic retrieval from the early Golgi compartment. We have also shown that Rer1p, a membrane protein in the Golgi, is required for correct localization of Sec12p. In the present study, we have performed a systematic analysis to determine the ER localization signals in Sec12p corresponding to these two mechanisms. Both the transmembrane domain (TMD) and the NH2-terminal cytoplasmic domain of Sec12p show the ability to localize the protein to the ER. The effect of the TMD is potent and sufficient by itself for the ER localization and is strongly dependent on Rer1p. On the other hand, the cytoplasmic domain shows a moderate ER-localization capability which is independent of Rer1p. The rate of mannosyl modification has been measured to distinguish between retention and retrieval. The cytoplasmic domain significantly delays the transport from the ER to the cis-Golgi. In contrast, the TMD shows only a subtle retardation in the transport from the ER to the cis-Golgi but strictly prevents the transport beyond there. From these observations, we conclude that the TMD mainly acts as the retrieval signal and the cytoplasmic domain contains the retention signal. This study not only supports the two-mechanisms hypothesis but also provides powerful tools to dissect the two.Keywords
This publication has 38 references indexed in Scilit:
- Inhibition of GTP hydrolysis by Sar1p causes accumulation of vesicles that are a functional intermediate of the ER-to-Golgi transport in yeastThe Journal of cell biology, 1994
- Oligomerization of a membrane protein correlates with its retention in the Golgi complexThe Journal of cell biology, 1993
- Cholesterol and the Golgi ApparatusScience, 1993
- Identification of a gene required for membrane protein retention in the early secretory pathway.Proceedings of the National Academy of Sciences of the United States of America, 1993
- SEC12 encodes a guanine-nucleotide-exchange factor essential for transport vesicle budding from the ERNature, 1993
- ERD2, a yeast gene required for the receptor-mediated retrieval of luminal ER proteins from the secretory pathwayCell, 1990
- Biogenesis of vacuolar membrane glycoproteins of yeast Saccharomyces cerevisiae.Journal of Biological Chemistry, 1990
- A novel GTP-binding protein, Sar1p, is involved in transport from the endoplasmic reticulum to the Golgi apparatus.The Journal of cell biology, 1989
- Structure, biosynthesis, and localization of dipeptidyl aminopeptidase B, an integral membrane glycoprotein of the yeast vacuole.The Journal of cell biology, 1989
- A colony procedure for transformation of Saccharomyces cerevisiaeCurrent Genetics, 1988