関連する実験動画
Updated: Jul 30, 2026

10:13
Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding
Published on: June 9, 2017
内分泌機能の増減を伴う患者でGsαからGDPの急速な放出
T Iiri1, P Herzmark, J M Nakamoto
1Department of Pharmacology, University of California, San Francisco 94143-0450.
Nature
|September 8, 1994
まとめ
新しいGsアルファサブユニット変異は,アデニリルサイクラスを構成的に活性化することによって,テストオキシキソシスと型Iaの擬似ヒポパラチロイド症の両方を引き起こします. この突然変異は,ホルモンに依存しないテストステロンの分泌と,体温でGsの活性低下につながる.
科学分野:
- エンドクリノロジー エンドクリノロジー
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
背景:
- ルテイン化ホルモン (LH) は,Gタンパク質Gsとアデニリルサイクラスを介して,レイディグ細胞のテストステロン産生を刺激する.
- 早期の思春期の形態であるテスト中毒症は,LH独立のテストステロン分泌を含み,しばしばルテイン化ホルモン受容体またはGs経路の変異によるものです.
- 型Ia (PHP-Ia) の偽甲状腺症は,ホルモン抵抗性 (例えば,甲状腺ホルモン,甲状腺刺激ホルモン) とGs活性低下によって特徴付けられます.
研究 の 目的:
- 2人の無縁の男の子のテストトキシコシスとPHP-Iaの希少な組み合わせの分子基礎を調査する.
- これらの患者で特定された特定のGsαサブユニット変異の機能的影響を明らかにする.
主な方法:
- Gsアルファサブユニット遺伝子の変異を特定するための遺伝子分析.
- 変異したGsアルファサブユニットを発現する培養細胞におけるアデニリルサイクラースの活性とcAMPの蓄積を評価するためのインビトロ研究.
- 変異したGsαサブユニットの温度安定性アッセイ.
主要な成果:
- 位置366のアラニンをセリン (alpha s-A366S) で置き換える変異が,両方の患者のGsアルファサブユニット遺伝子で確認されました.
- アルファs-A366S変異は構成的にアデニリルサイクラスを活性化し,ホルモン独立のcAMP蓄積につながり,テストトキシコシス現象型を説明します.
- アルファs-A366Sタンパク質は丸の温度では安定していたが,37°Cでは急速に分解し,Gs活性喪失によるPHP-Iaフェノタイプを説明する.
結論:
- アルファs-A366S変異は,テスト毒性症とPHP-Iaの二重フェノタイプの原因である.
- 変異したGsαサブユニットからのGDPの加速放出は,その構成活動と熱可変性の両方を裏づけています.
- この研究は,異なる内分泌経路におけるGsタンパク質機能と温度感受性の重要な役割を強調しています.
関連する概念動画
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
GPCR Desensitization
G protein-coupled receptor (GPCR) signaling plays a crucial role in cell functioning. GPCR desensitization is an equally essential process. It allows cells to respond to changing environments and regain sensitivity to new stimuli while preventing unnecessary stimulation when no longer needed. Prolonged exposure to stimuli leads to GPCR desensitization. It involves blocking the receptors from binding and activating additional G proteins. This inhibits activation of downstream effectors, thereby...
GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
Major Hormones and Their Functions
Hormones, the biochemical messengers produced by endocrine glands, are pivotal in regulating bodily functions and maintaining homeostasis. Each hormone's balance is crucial; imbalances can lead to significant physiological disruptions. Major hormones include oxytocin, cortisol, epinephrine, estrogen, testosterone, thyroxine, growth hormone, insulin, and glucagon.
Oxytocin, produced in the hypothalamus and released by the pituitary gland, plays a role in social bonding, childbirth, and lactation.
Oxytocin, produced in the hypothalamus and released by the pituitary gland, plays a role in social bonding, childbirth, and lactation.

