Journal Article

MAG4/Atp115 is a Golgi-Localized Tethering Factor that Mediates Efficient Anterograde Transport in <i>Arabidopsis</i>

Hideyuki Takahashi, Kentaro Tamura, Junpei Takagi, Yasuko Koumoto, Ikuko Hara-Nishimura and Tomoo Shimada

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 10, pages 1777-1787
Published in print October 2010 | ISSN: 0032-0781
Published online September 2010 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcq137
MAG4/Atp115 is a Golgi-Localized Tethering Factor that Mediates Efficient Anterograde Transport in Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Seed storage proteins are synthesized on rough endoplasmic reticulum (ER) in a precursor form and then are transported to protein storage vacuoles (PSVs) where they are converted to their mature form. To understand the mechanisms by which storage proteins are transported, we screened Arabidopsis maigo mutants to identify those that abnormally accumulate storage protein precursors. Here we describe a new maigo mutant, maigo 4 (mag4), that abnormally accumulates the precursors of two major storage proteins, 12S globulin and 2S albumin, in dry seeds. Electron microscopy revealed that mag4 seed cells abnormally develop a large number of novel structures that exhibit a highly electron-dense core. Some of these structures were surrounded by ribosomes. Immunogold analysis suggests that the electron-dense core is an aggregate of 2S albumin precursors and that 12S globulins are localized around the core. The MAG4 gene was identified as At3g27530, and the MAG4 protein has domains homologous to those found in bovine vesicular transport factor p115. MAG4 molecules were concentrated at cis-Golgi stacks. Our findings suggest that MAG4 functions in the transport of storage protein precursors from the ER to the Golgi complex in plants. In addition, the mag4 mutant exhibits a dwarf phenotype, suggesting that MAG4 is involved in both the transport of storage proteins and in plant growth and development.

Keywords: Golgi complex; Storage protein; Tethering factor; Vacuole; Vesicle transport

Journal Article.  5849 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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