An Arabidopsis GRIP domain protein locates to the trans-Golgi and binds the small GTPase ARL1.
GRIP domain proteins are a class of golgins that have been described in yeast and animals. They locate to the trans-Golgi network and are thought to play a role in endosome-to-Golgi trafficking. The Arabidopsis GRIP domain protein, AtGRIP, fused to the green fluorescent protein (GFP), locates to Golgi stacks but ... does not exactly co-locate with the Golgi marker sialyl transferase (ST)-mRFP, nor with the t-SNAREs Memb11, SYP31 and BS14a. We conclude that the location of AtGRIP is further to the trans side of the stack than STtmd-mRFP. The 185-aa C-terminus of AtGRIP containing the GRIP domain targeted GFP to the Golgi, although a proportion of the fusion protein was still found in the cytosol. Mutation of a conserved tyrosine (Y717) to alanine in the GRIP domain disrupted Golgi localization. ARL1 is a small GTPase required for Golgi targeting of GRIP domain proteins in other systems. An Arabidopsis ARL1 homologue was isolated and shown to target to Golgi stacks. The GDP-restricted mutant of ARL1, AtARL1-T31N, was observed to locate partially to the cytosol, whereas the GTP-restricted mutant AtARL1-Q71L labelled the Golgi and a population of small structures. Increasing the levels of AtARL1 in epidermal cells increased the proportion of GRIP-GFP fusion protein on Golgi stacks. We show, moreover, that AtARL1 interacted with the GRIP domain in a GTP-dependent manner in vitro in affinity chromatography and in the yeast two-hybrid system. This indicates that AtGRIP and AtARL1 interact directly. We conclude that the pathway involving ARL1 and GRIP domain golgins is conserved in plants.
Mesh Terms:
Amino Acid Sequence, Amino Acid Substitution, Arabidopsis, Arabidopsis Proteins, Gene Expression Regulation, Plant, Membrane Proteins, Molecular Sequence Data, Monomeric GTP-Binding Proteins, Mutation, Plants, Genetically Modified, Protein Binding, Protein Structure, Tertiary, Protein Transport, Sequence Homology, Amino Acid, Tobacco, trans-Golgi Network
Amino Acid Sequence, Amino Acid Substitution, Arabidopsis, Arabidopsis Proteins, Gene Expression Regulation, Plant, Membrane Proteins, Molecular Sequence Data, Monomeric GTP-Binding Proteins, Mutation, Plants, Genetically Modified, Protein Binding, Protein Structure, Tertiary, Protein Transport, Sequence Homology, Amino Acid, Tobacco, trans-Golgi Network
Plant J.
Date: Nov. 01, 2005
PubMed ID: 16236155
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