The Yeast Arf GTPase-activating Protein Age1 Is Regulated by Phospholipase D for Post-Golgi Vesicular Transport

Department of Microbiology and Immunology, DalhousieUniversity, Halifax, Nova Scotia B3H 1X5, Canada.
Journal of Biological Chemistry (Impact Factor: 4.57). 02/2011; 286(7):5187-96. DOI: 10.1074/jbc.M110.185108
Source: PubMed


Vesicular transport shuttles cargo among intracellular compartments. Several stages of vesicular transport are mediated by
the small GTPase Arf, which is controlled in a cycle of GTP binding and hydrolysis by Arf guanine-nucleotide exchange factors
and Arf GTPase-activating proteins (ArfGAPs), respectively. In budding yeast the Age2 + Gcs1 ArfGAP pair facilitates post-Golgi
transport. We have found the AGE1 gene, encoding another ArfGAP, can in high gene-copy number alleviate the temperature sensitivity of cells carrying mutations
affecting the Age2 + Gcs1 ArfGAP pair. Moreover, increased AGE1 gene dosage compensates for the complete absence of the otherwise essential Age2 + Gcs1 ArfGAP pair. Increased dosage of
SFH2, encoding a phosphatidylinositol transfer protein, also allows cell growth in the absence of the Age2 + Gcs1 pair, but good
growth in this situation requires Age1. The ability of Age1 to overcome the need for Age2 + Gcs1 depends on phospholipase
D activity that regulates lipid composition. We show by direct assessment of Age1 ArfGAP activity that Age1 is regulated by
lipid composition and can provide ArfGAP function for post-Golgi transport.

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    • "The Sorting nexin family (Table 3) regulates endosomal sorting of internalized proteins through modulating endosomal-to-lysosomal sorting (Carlton et al., 2004). Both elevated Arf GTPase (Tables 1 and 3) or attenuated Arf GTPase activating protein family (Table 4) expression may help maintain Arf GTPase activity which is essential for the recruitment of coat protein complex I and clathrin coat complexes needed for the generation of transport vesicles (Benjamin et al., 2011). "
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    • "Arl1-His6 and Arf1-His6 were each coexpressed with N-myristoyltransferase in BL21(DE3) bacterial cells and purified following the procedure to isolate Arf1-His6 as described (Benjamin et al., 2011). Myristoylated GTPase was loaded with radioactive GTP, and GAP activity was assessed as described (Huber et al., 2001; Poon et al., 2001). "
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