We have cloned and characterized members of a novel family of proteins, the GGAs. These proteins contain an NH2-terminal VHS domain, one or two coiled-coil domains, and a COOH-terminal domain homologous to the COOH-terminal “ear” domain of γ-adaptin. However, unlike γ-adaptin, the GGAs are not associated with clathrin-coated vesicles or with any of the components of the AP-1 complex. GGA1 and GGA2 are also not associated with each other, although they colocalize on perinuclear membranes. Immunogold EM shows that these membranes correspond to trans elements of the Golgi stack and the TGN. GST pulldown experiments indicate that the GGA COOH-terminal domains bind to a subset of the proteins that bind to the γ-adaptin COOH-terminal domain. In yeast there are two GGA genes. Deleting both of these genes results in missorting of the vacuolar enzyme carboxypeptidase Y, and the cells also have a defective vacuolar morphology phenotype. These results indicate that the function of the GGAs is to facilitate the trafficking of proteins between the TGN and the vacuole, or its mammalian equivalent, the lysosome.
A Family of Proteins with γ-Adaptin and Vhs Domains That Facilitate Trafficking between the Trans-Golgi Network and the Vacuole/Lysosome
The online version of this article contains supplemental material.
Abbreviations used in this paper: CPY, carboxypeptidase Y; EAST, epidermal growth factor receptor-associated protein with SH3 and TAM domains; EH, Eps15 homology; GGAs, Golgi-localized, γ ear-containing, ARF-binding proteins; Hrs, hepatocyte growth factor-regulated tyrosine kinase substrate; MALDI, matrix assisted laser desorption ionization; NRK, normal rat kidney; STAM, signal transducing adaptor molecule; VHS domains, domains containing proteins Vps27p, Hrs, and STAM.
Jennifer Hirst, Winnie W.Y. Lui, Nicholas A. Bright, Nicholas Totty, Matthew N.J. Seaman, Margaret S. Robinson; A Family of Proteins with γ-Adaptin and Vhs Domains That Facilitate Trafficking between the Trans-Golgi Network and the Vacuole/Lysosome. J Cell Biol 3 April 2000; 149 (1): 67–80. doi: https://doi.org/10.1083/jcb.149.1.67
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