Recoverin: 網膜棒のガニラートサイクラースのカルシウムに敏感な活性化剤
1Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR.
まとめ
新しいカルシウム結合タンパク質であるリカベリンは,脊椎動物の網膜の光受容体におけるギュアニラートサイクラスを調節する. このタンパク質は,周期的なGMP合成を制御することによって,光にさらされた後の視力を回復するために不可欠です.
科学分野:
- 分子生物学は分子生物学である.
- 神経科学は神経科学である.
- バイオケミストリー バイオケミストリー
背景:
- 脊椎動物の網膜の光受容体は,光にさらされた後に,循環性GMP (グアナシン3',5'-モノフォスファート) を再合成することによって再生する.
- 光に誘発されたカルシウム減少は,光受容体の回復の重要なステップであるグアニラートサイクラスを活性化します.
研究 の 目的:
- 光受容体回復におけるガニラートサイクラスを調節するカルシウム結合タンパク質を特定し,特徴づけること.
- この新しいタンパク質が視覚サイクルにおける役割を調査する.
主な方法:
- カルシウム-45.5を使用したカルシウム結合測定法.
- トリプトファン光スペクトロスコーピーは,カルシウムによって引き起こされる形状の変化を検出します.
- 特定されたタンパク質に対する抗体による免疫学的ブロック.
- グアニラートサイクラゼの酵素活性測定法.
主要な成果:
- 23キロダルトンのカルシウム結合タンパク質の"リカバリン"がロッドとコーンの両方の光受容体で特定されました.
- リカベリンは,細胞塩酸カルシウム濃度が低下する (450 nM から 40 nM) 時にガニア酸サイクラスを活性化します.
- カルシウムなしのリカベリンは,網膜棒のグアニラートサイクラスを刺激し,暗黒状態の回復を促進します.
結論:
- Recoverinは,光受容体における視力の回復に不可欠な,グアニラートサイクラスの重要な調節剤です.
- リカベリンは,ビシニンと共に,サブマイクロモラーカルシウム濃度によって調節されるタンパク質ファミリーを形成する可能性があります.
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