植物の皮質性脂質の輸出には,ABCトランスポーターが必要です
Jamie A Pighin1, Huanquan Zheng, Laura J Balakshin
1Department of Botany, University of British Columbia (UBC), 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada.
Science (New York, N.Y.)
|October 23, 2004
まとめ
アラビドプシスCER5遺伝子は,表皮細胞から植物の表面にクティキュラーワックスを輸出するために不可欠なプラズマ膜ABCトランスポーターをコードします.
科学分野:
- 植物生物学 植物生物学
- 細胞生物学 細胞生物学
- バイオケミストリー バイオケミストリー
背景:
- 植物には,保護のために状の皮質があり,表皮細胞からの重要な脂質の輸出を必要とします.
- アラビドプシス (Arabidopsis cer5) の突然変異は,皮質のの蓄積を妨害し,細胞プラズマの挿入につながります.
研究 の 目的:
- cer5変異フェノタイプに起因する遺伝子を特定する.
- 皮質のの生物合成と輸送におけるCER5遺伝子の機能を明らかにする.
主な方法:
- アラビドプシス (Arabidopsis cer5) の変異体で,皮質のが減少した分析.
- ワックスを分泌する細胞の顕微鏡検査で,細胞プラズマインクルージョンを特定する.
- 遺伝子識別とタンパク質の局所化に関する研究.
主要な成果:
- アラビドプシス・サー5変異種は,幹の皮質のが減少し,異常な細胞プラズマの挿入を示しています.
- これらのインクルージョンは,堆積したクティキュラーワックスで構成されています.
- CER5遺伝子は,表皮細胞のプラズマ膜に局限されたペロキシソーマルABCトランスポーターをコードする.
結論:
- CER5遺伝子は,皮質のの輸送に不可欠です.
- ABCトランスポーターであるCER5タンパク質は,表皮細胞から皮質へのの輸出を促進します.
- CER5の欠陥により,の輸出が損なわれ,細胞内に異常なの蓄積が起こります.
関連する概念動画
01:31ABC Transporters: Exporter
ATP-binding cassette or ABC transporter is the largest superfamily of integral membrane proteins. The transporters have transmembrane-binding domains (TMDs) and nucleotide-binding domains (NBDs). The TMDs are specific to their substrates, whereas the NBDs are similar to engines that complete ATP hydrolysis to complete the substrate transport. They can be full transporters consisting of two TMDs and NBDs, half transporters with one TMD and NBD, while some encoded with a single TMD or NBD are...
01:27ABC Transporters: Importer
ATP-binding cassette or ABC transporters are a class of ATP-driven pumps that hydrolyze ATP to move solutes across the membrane. They can be grouped into importers and exporters. While exporters are present in all domains of life, importers exist only in bacteria and some plants.
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
01:24Protein Transport to the Stroma
Chloroplasts are triple membrane structures with an outer membrane, an inner membrane, and a thylakoid membrane, each containing distinct metabolite transporters, membrane translocons, and enzymes. Appropriate sorting and translocating these proteins to their correct membrane systems is essential for chloroplast function.
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
01:11Protein Transport to the Outer Chloroplast Membrane
Chloroplast outer membrane proteins encoded by the nucleus are synthesized in the cytosol. Soon after synthesis, they bind cytosolic factors such as 14-3-3 protein and the Hsp70 chaperones that keep these precursors in an unfolded state until their translocation.
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
01:06Fats as Energy Storage Molecules
Triglycerides are a form of long-term energy storage molecules. They are made of glycerol and three fatty acids. To obtain energy from fat, triglycerides must first be broken down by hydrolysis into their two principal components, fatty acids and glycerol. This process, called lipolysis, takes place in the cytoplasm. The resulting fatty acids are oxidized by β-oxidation into acetyl-CoA, which is used by the Krebs cycle. The glycerol that is released from triglycerides after lipolysis directly...
01:24Lipid Absorption
Dietary triglycerides from chyme in the duodenum are mixed with bile salts produced by the liver to emulsify fats. As a result, large droplets are broken down into smaller ones, increasing the surface area for enzymatic action. Once emulsified, pancreatic lipases hydrolyze the triglycerides into free fatty acids and monoglycerides.
These breakdown products bind with bile salts and lecithin to form micelles, which quickly pass between microvilli to come in close contact with the apical...
These breakdown products bind with bile salts and lecithin to form micelles, which quickly pass between microvilli to come in close contact with the apical...