Identification and Dynamics of Arabidopsis Adaptor Protein-2 Complex and Its Involvement in Floral Organ Development |
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Authors: | Shohei Yamaoka Yuki Shimono Makoto Shirakawa Yoichiro Fukao Takashi Kawase Noriyuki Hatsugai Kentaro Tamura Tomoo Shimada Ikuko Hara-Nishimura |
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Affiliation: | aGraduate School of Science, Kyoto University, Kyoto 606-8502, Japan;bGraduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan;cPlant Global Educational Project, Nara Institute of Science and Technology, Ikoma 630-0192, Japan;dResearch Center for Cooperative Projects, Hokkaido University, Sapporo 060-8638, Japan |
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Abstract: | The adaptor protein-2 (AP-2) complex is a heterotetramer involved in clathrin-mediated endocytosis of cargo proteins from the plasma membrane in animal cells. The homologous genes of AP-2 subunits are present in the genomes of plants; however, their identities and roles in endocytic pathways are not clearly defined in plants. Here, we reveal the molecular composition of the AP-2 complex of Arabidopsis thaliana and its dynamics on the plasma membrane. We identified all of the α-, β-, σ-, and μ-subunits of the AP-2 complex and detected a weak interaction of the AP-2 complex with clathrin heavy chain. The μ-subunit protein fused to green fluorescent protein (AP2M-GFP) was localized to the plasma membrane and to the cytoplasm. Live-cell imaging using a variable-angle epifluorescence microscope revealed that AP2M-GFP transiently forms punctate structures on the plasma membrane. Homozygous ap2m mutant plants exhibited abnormal floral structures, including reduced stamen elongation and delayed anther dehiscence, which led to a failure of pollination and a subsequent reduction of fertility. Our study provides a molecular basis for understanding AP-2–dependent endocytic pathways in plants and their roles in floral organ development and plant reproduction. |
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