まとめ
海の卵キネシンは微小管で活性化されたATPアゼ活性を示しており,その運動性はATP水解と結びついていることを示唆しています. この発見は,キネシン駆動マイクロチューブル運動のクロスブリッジメカニズムを支持する.
科学分野:
- 細胞生物学 細胞生物学
- 分子モーターは分子モーターです.
- バイオケミストリー バイオケミストリー
背景:
- ダイネインやキネシンなどの微小管ベースのモーターは,細胞内輸送と細胞分裂に不可欠です.
- ダイネインのATP水解は,クロスブリッジメカニズムを通じてマイクロチューブルの滑り方を誘導することが知られている.
- キネシンのヌクレオチド感受性結合と微小管の転位は,同様のメカニズムを示唆しているが,ATP水解と運動性の直接的な結合は証明されていない.
研究 の 目的:
- 海の卵キネシンのATP水解と運動性の関係を調査する.
- キネシンのATPアゼ活性がマイクロチューブルによって活性化され,その運動機能と結合されているかどうかを判断する.
主な方法:
- 浄化された海膽卵キネシンは,5'-アデニリルイミドジフォスファート (AMPPNP) マイクロチューブル結合ステップを使用するか,または無しに準備されました.
- 微小管で活性化されたATPアゼの活性度は,基板としてMg-ATPを用いて測定されました.
- 様々な阻害剤 (MgフリーATP,EDTA,Na3VO4,AMPPNP) がATP酶活性と微小管転位の両方に与える影響を評価した.
主要な成果:
- 海の卵キネシンは,微小管で活性化されたMg2+-ATPaseの有意な活性を示した.
- このATP酵素の活動は,MgフリーATP,EDTA,Na3VO4,AMPPNPによって,投与量に依存して抑制された.
- ATPaseの活性を阻害した同じ反応剤は,キネシンによるマイクロチューブル転位を阻害した.
結論:
- キネシン駆動のマイクロチューブル転位は,マイクロチューブル活性化Mg2+-ATPase活性と結びついています.
- これは,ミオシンと同様の,キネシン運動性のクロスブリッジメカニズムをサポートしています.
- この発見は,キネシンベースの輸送におけるエネルギー伝導機構の直接的な証拠を提供します.
関連する概念動画
Destabilization of Microtubules
The destabilization of microtubules can occur during different stages of the microtubule lifecycle, such as nucleation or elongation. It can take place at either end of the microtubule or in the microtubule lattices as a whole. The lifespan of individual microtubules within a cell varies according to the cell type and stage of the cell cycle. During interphase, the lifespan of the microtubule is about 30 minutes, while during cell division, it is about 15 minutes. In axonal microtubules of...
Microtubule Associated Motor Proteins
Eukaryotic cells have different motor proteins for transporting various cargo within the cell. These motor proteins differ based on the filament they associate with, the direction they move within the cell, and the type of cargo they transport. Motor proteins that associate with microtubules are known as microtubule-associated motor proteins. There are two families of microtubule-associated motor proteins —Kinesins and Dyneins. Both these proteins assist in the transport of cellular cargos...
The Movement of Organelles and Vesicles
In eukaryotic cells, cytoskeletal filaments such as actin, microtubules, and intermediate filaments form a mesh-like cytoskeletal network. These filaments serve as tracks for transporting cellular cargo. Specialized motor proteins use the chemical energy stored in adenosine triphosphate (ATP) for this transport. During interphase, microtubules are polarized, with the plus-end towards the cell periphery and the minus-end towards the cell center. Two microtubule-associated motor proteins,...
Microtubules in Cell Motility
Microtubules are thick hollow cylindrical proteins that help form the cytoskeleton. Microtubules have varied roles in the cell. These filaments help form cellular appendages like cilia and flagella, which are responsible for locomotion. The cilia arise from basal bodies, separated from the main body by a membrane-like structure forming the transition zone. This zone is the gate for the entry of lipids and proteins, creating a unique composition of lipids and proteins in the ciliary membrane and...
Forces Acting on Chromosomes
During mitosis, chromosome movements occur through the interplay of multiple piconewton level forces. In prometaphase, these forces help in chromosome assembly or congression at the equatorial plane, eventually leading to their alignment at the metaphase plate. The forces acting on the chromosomes are space and time-dependent; therefore, they vary with the position of the chromosomes as the cell progresses through mitosis.
Microtubules and motor proteins exert two types of forces on...
Microtubules and motor proteins exert two types of forces on...
Anaphase A and B
Microtubules form through the end-to-end polymerization of tubulin heterodimers. Kinetochore microtubules originate from the spindle poles, and their plus-ends connect with the kinetochores on sister-chromatids. Ndc80 protein complexes, present on the kinetochore, form low-affinity links with the plus end of these kinetochore microtubules.
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...


