Increased cardiac contractility during the fight-or-flight response is caused by β-adrenergic augmentation of Ca_V1.2 voltage-gated calcium channels^1,2,3,4. However, this augmentation persists in transgenic murine hearts expressing mutant Ca_V1.2 α_1C and β subunits that can no longer be phosphorylated by protein kinase A—an essential downstream mediator of β-adrenergic signalling—suggesting that non-channel factors are also required. Here we identify the mechanism by which β-adrenergic agonists stimulate voltage-gated calcium channels. We express α_1C or β_2B subunits conjugated to ascorbate peroxidase⁵ in mouse hearts, and use multiplexed quantitative proteomics^6,7 to track hundreds of proteins in the proximity of Ca_V1.2. We observe that the calcium-channel inhibitor Rad^8,9, a monomeric G protein, is enriched in the Ca_V1.2 microenvironment but is depleted during β-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for β subunits and relieves constitutive inhibition of Ca_V1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of Ca_V1.3 and Ca_V2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels.

战斗或逃跑反应期间心肌收缩力增加是由 Ca _V 1.2 电压门控钙通道^1,2,3,4的 β-肾上腺素能增强引起的。然而，这种增强作用在表达突变 Ca _V 1.2 α _1C和 β 亚基的转基因小鼠心脏中持续存在，这些亚基不再被蛋白激酶 A（β-肾上腺素信号传导的重要下游介质）磷酸化，这表明还需要非通道因子。在这里，我们确定了 β-肾上腺素能激动剂刺激电压门控钙通道的机制。我们在小鼠心脏中表达与抗坏血酸过氧化物酶⁵缀合的 α _1C或 β _2B亚基，并使用多重定量蛋白质组学^6,7追踪 Ca _V 1.2 附近的数百种蛋白质。我们观察到钙通道抑制剂 Rad ^8,9是一种单体 G 蛋白，在 Ca _V 1.2 微环境中富集，但在 β-肾上腺素能刺激过程中被耗尽。蛋白激酶 A 对 Rad 上特定丝氨酸残基的磷酸化降低了其对 β 亚基的亲和力，并减轻了 Ca _V 1.2 的组成型抑制，观察到通道开放概率增加。 HEK293T 细胞中 Rad 或其同源物 Rem 的表达也会通过蛋白激酶 A 刺激 Ca _V 1.3 和 Ca _V 2.2，揭示了一种进化上保守的机制，可对电压门控钙通道进行肾上腺素能调节。