Akt媒介によるNADキナーゼのリン酸化によるNADP+合成の直接刺激
Gerta Hoxhaj1, Issam Ben-Sahra2, Sophie E Lockwood1
1Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
まとめ
成長因子シグナリングは,Aktのリン酸化によってNADキナーゼ (NADK) を活性化し,代謝に不可欠なNADP+の産生を促進します. この調節は,還元性細胞プロセスのためのNADPHの可用性を高めます.
科学分野:
- 細胞の代謝
- 信号変換
- 酵素調節
背景:
- ニコチナミドアデニンジヌクレオチドリン酸 (NADP+) は,主にその縮小形であるNADPHを通じて,還元代謝に不可欠です.
- 成長因子のシグナル伝達経路は,細胞の代謝調節に重要な役割を果たします.
- NADキナーゼ (NADK) は,NADP+の合成を担う重要な酵素である.
研究 の 目的:
- NADP+とNADPH合成の調節におけるフォスフォノシチド3キナーゼ (PI3K) - アクト経路の役割を調査する.
- AktがNADKの活動に影響を与えるメカニズムを解明する.
- 成長因子シグナリングによってNADP+の生成が急激に調節される方法を理解する.
主な方法:
- 細胞内のNADP+とNADPHレベルに対する成長因子のシグナル効果を調査した.
- AktによるNADKのリン酸化を in vitroで研究するために生化学的測定を用いた.
- 調節性アミノ端末ドメインが欠けているものを含め,NADKイソフォームの活性を分析した.
主要な成果:
- PI3K-Akt経路による成長因子のシグナル伝達は,NADP+とNADPHの合成を急激に増加させる.
- Aktは,特定のセリン残基 (Ser44,Ser46,Ser48) に NADK を直接リン酸化し,その酵素活性を増強する.
- 酸化部位が欠けている天然に存在するNADK同型 (同型3) は,自己抑制を示唆する構成性の高い活性を示している.
結論:
- NADKのAkt媒介型リン酸化は,NADP+の産生を刺激する重要なメカニズムである.
- このリン酸化はNADKのアミノ末端の自己抑制機能を緩和し,その触媒効率を高めます.
- 成長因子のシグナル伝達と重要な代謝コファクターの調節との間には直接的な関連があることが明らかになった.
関連する概念動画
Protein Kinases and Phosphatases
15.1K
Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis are various protein modifications that regulate protein activity. Such modifications are usually enzyme-driven.
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
15.1K
Protein Kinases and Phosphatases
4.5K
4.5K
Phosphorylation
53.8K
The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications can affect the structure, activity, stability, and localization of proteins within cells as well as their interactions with other proteins.
During phosphorylation, protein kinases transfer the terminal phosphate group of ATP to specific amino acid side chains of substrate proteins. Serine, threonine, and tyrosine are the most commonly...
During phosphorylation, protein kinases transfer the terminal phosphate group of ATP to specific amino acid side chains of substrate proteins. Serine, threonine, and tyrosine are the most commonly...
53.8K
PI3K/mTOR/AKT Signaling Pathway
5.4K
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a...
5.4K
Lagging Strand Synthesis
61.3K
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
61.3K
Nonsense-mediated mRNA Decay
11.8K
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
11.8K


