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| H-ras but not K-ras traffics to the plasma membrane through the exocytic pathway |
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| Author(s): Apolloni A, Prior IA, Lindsay M, Parton RG, Hancock JF |
| Source: MOLECULAR AND CELLULAR BIOLOGY Volume: 20 Issue: 7 Pages: 2475-2487 Published: APR 2000 |
| Times Cited: 196 References: 59 |
| Abstract: Ras proteins must be localized to the inner surface of the plasma membrane to be biologically active. The motifs that effect Ras plasma membrane targeting consist of a C-terminal CAAX motif plus a second signal comprising palmitoylation of adjacent cysteine residues or the presence of a polybasic domain. In this study, we examined how Ras proteins access the cell surface after processing of the CAAX motif is completed in the endoplasmic reticulum (ER). We show that palmitoylated CAAX proteins, in addition to being localized at the plasma membrane, are found throughout the exocytic pathway and accumulate in the Golgi region when cells are incubated at 15 degrees C. In contrast, polybasic CAAX proteins are found only at the cell surface and not in the exocytic pathway. CAAX proteins which lack a second signal for plasma membrane targeting accumulate in the ER and Golgi. Brefeldin A (BFA) significantly inhibits the plasma membrane accumulation of newly synthesized, palmitoylated CAAX proteins without inhibiting their palmitoylation. BFA has no effect on the trafficking of polybasic CAAX proteins. We conclude that H-ras and K-ras traffic to the cell surface through different routes and that the polybasic domain is a sorting signal diverting K-Ras out of the classical exocytic pathway proximal to the Golgi. Farnesylated Ras proteins that lack a polybasic domain reach the Golgi but require palmitoylation in order to traffic further to the cell surface. These data also indicate that a Ras palmitoyltransferase is present in an early compartment of the exocytic pathway. |
| Document Type: Article |
| Language: English |
| Reprint Address: Hancock, JF (reprint author), Univ Queensland, Sch Med, Dept Pathol, Queensland Canc Fund Lab Expt Oncol, Herston Rd, Brisbane, Qld 4069 Australia |
Addresses:
1. Univ Queensland, Sch Med, Dept Pathol, Queensland Canc Fund Lab Expt Oncol, Brisbane, Qld 4069 Australia
2. Univ Queensland, Dept Physiol & Pharmacol, Ctr Cellular & Mol Biol, Brisbane, Qld 4069 Australia
3. Univ Queensland, Dept Physiol & Pharmacol, Ctr Microscopy & Microanal, Brisbane, Qld 4069 Australia |
| Publisher: AMER SOC MICROBIOLOGY, 1325 MASSACHUSETTS AVENUE, NW, WASHINGTON, DC 20005-4171 USA |
| Subject Category: Biochemistry & Molecular Biology; Cell Biology |
| IDS Number: 292RQ |
| ISSN: 0270-7306 |
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