Lowenstein W R
Biochem Soc Symp. 1985;50:43-58.
The cyclic AMP-activated protein kinase I, a serine- and threonine-phosphorylating enzyme, regulates cell-to-cell communication. Its deficiency in mutant cells is associated with deficiency of communication. The communication defect is corrected by introduction of the catalytic subunit of the enzyme into the mutant cells. Activation of the enzyme by cyclic AMP in normal cells causes an increase of communication, namely an increase of junctional permeability associated with an increase in the number of membrane particles of gap junction. This upregulation of cell-to-cell membrane channels constitutes a basic mechanism whereby cell communities set their degree of communication. The mechanism is normally put into motion by adenylate cyclase-activating hormones. The mechanism is counteracted by tyrosine-phosphorylating protein kinase (src protein), which downregulates junctional permeability, a fast and reversible effect on the channels, independent of the action of the kinase on the cytoskeleton. The two T proteins coded by the SV-40 genome cause a similar channel downregulation.
环磷酸腺苷激活的蛋白激酶I是一种丝氨酸和苏氨酸磷酸化酶，可调节细胞间通讯。其在突变细胞中的缺陷与通讯缺陷相关。通过将该酶的催化亚基引入突变细胞可纠正通讯缺陷。正常细胞中环磷酸腺苷对该酶的激活会导致通讯增加，即连接通透性增加，同时伴随着间隙连接膜颗粒数量的增加。这种细胞间膜通道的上调构成了细胞群落设定其通讯程度的基本机制。该机制通常由激活腺苷酸环化酶的激素启动。酪氨酸磷酸化蛋白激酶（src蛋白）可抵消该机制，src蛋白会下调连接通透性，这是对通道的一种快速且可逆的作用，与激酶对细胞骨架的作用无关。由SV - 40基因组编码的两种T蛋白会导致类似的通道下调。
