Identification and Dynamics of Arabidopsis Adaptor Protein-2 Complex and Its Involvement in Floral Organ Development

• Published in: The Plant cell Vol. 25; no. 8; pp. 2958 - 2969
• Main Authors: Yamaoka, Shohei, Shimono, Yuki, Shirakawa, Makoto, Fukao, Yoichiro, Kawase, Takashi, Hatsugai, Noriyuki, Tamura, Kentaro, Shimada, Tomoo, Hara-Nishimura, Ikuko
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01-08-2013
• Subjects: Adaptor Protein Complex 2 - metabolism; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis - ultrastructure; Arabidopsis Proteins - metabolism; Cell Membrane - metabolism; Cell membranes; Developmental biology; Endocytosis; Epidermal cells; Flowers - growth & development; Flowers - metabolism; Flowers - ultrastructure; Fluorescence; Freight; Green Fluorescent Proteins - metabolism; Homozygote; Mutation - genetics; Plant cells; Plant Development; Plants; Pollen - growth & development; Pollen - metabolism; Pollen - ultrastructure; Protein Transport; Seedlings; Stamens; Tyrosine - metabolism
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.113.114082

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.