Beebe S J
Department of Physiology, Eastern Virginia Medical School, Norfolk 23501-1980.
Semin Cancer Biol. 1994 Aug;5(4):285-94.
The cAMP signal transduction system is one of several second messenger-dependent pathways that generates intracellular responses to extracellular signals. The primary element in this cascade is the cAMP-dependent protein kinases (PKA), which mediate most cAMP actions by phosphorylation. Regulatory subunit isoforms bind cAMP and localize catalytic subunit isoforms near substrate proteins. C-subunit isoforms also may have specific roles in PKA function. Compared to the C alpha-subunit isoform, C gamma has a more limited distribution, a different substrate and inhibitor specificity, and appears to require higher levels of cAMP for activation. Many PKA isoforms with differing localization, regulatory, and kinetic properties are thus possible. The potential roles for R- and C-subunits are discussed in the broad context of cAMP/PKA-mediated cell function.
环磷酸腺苷（cAMP）信号转导系统是几种依赖第二信使的信号通路之一，可产生细胞内对细胞外信号的反应。该级联反应的主要元件是依赖cAMP的蛋白激酶（PKA），其通过磷酸化介导大多数cAMP的作用。调节亚基异构体结合cAMP并将催化亚基异构体定位在底物蛋白附近。C亚基异构体在PKA功能中也可能具有特定作用。与Cα亚基异构体相比，Cγ分布更有限，具有不同的底物和抑制剂特异性，并且似乎需要更高水平的cAMP才能激活。因此，可能存在许多具有不同定位、调节和动力学特性的PKA异构体。本文在cAMP/PKA介导的细胞功能这一广泛背景下讨论了R亚基和C亚基的潜在作用。
