Sahyoun N, LeVine H, Stenbuck P, Cuatrecasas P
Proc Natl Acad Sci U S A. 1983 Jun;80(12):3646-50. doi: 10.1073/pnas.80.12.3646.
Rat liver and isolated hepatocytes contain high levels of a soluble adenylate cyclase stimulator, whereas rat erythrocytes lack this activity. Accordingly, a reconstitution system was developed with adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] from erythrocyte ghosts and the soluble activator from liver cytosol. Pretreatment of erythrocyte ghosts with the cytosolic factor resulted in a 5- to 15-fold activation of adenylate cyclase in the presence or absence of NaF, 5'-guanylyl imidodiphosphate, or isoproterenol and GTP. The sequence of addition of the cytosolic component and the other activators was critical in determining the maximal activity of the enzyme. The cytosolic factor appears to be a heat-labile Mr 105,000 protein, which activates adenylate cyclase in a saturable reaction involving binding of the protein to the erythrocyte ghosts. This molecular interaction was accompanied by stabilization of a labile thiol group that was essential for catalytic activity. The cytosolic component also unmasks latent adenylate cyclase activity in human erythrocyte ghosts and in cytoskeletal preparations from rat erythrocyte ghosts. These observations suggest that the cytosolic activator may also occur as a native, peripheral membrane component of adenylate cyclase systems and may be required for the expression and stabilization of catalytic activity.
大鼠肝脏和分离的肝细胞含有高水平的可溶性腺苷酸环化酶刺激剂，而大鼠红细胞则缺乏这种活性。因此，利用来自红细胞血影的腺苷酸环化酶[ATP焦磷酸裂解酶（环化），EC 4.6.1.1]和来自肝细胞溶质的可溶性激活剂开发了一种重组系统。用细胞溶质因子预处理红细胞血影，在存在或不存在氟化钠、5'-鸟苷酰亚胺二磷酸、异丙肾上腺素和鸟苷三磷酸的情况下，腺苷酸环化酶的活性可提高5至15倍。细胞溶质成分和其他激活剂的添加顺序对于确定该酶的最大活性至关重要。细胞溶质因子似乎是一种热不稳定的分子量为105,000的蛋白质，它通过涉及该蛋白质与红细胞血影结合的饱和反应来激活腺苷酸环化酶。这种分子相互作用伴随着对催化活性至关重要的不稳定硫醇基团的稳定。细胞溶质成分还可揭示人红细胞血影和大鼠红细胞血影细胞骨架制剂中潜在的腺苷酸环化酶活性。这些观察结果表明，细胞溶质激活剂也可能作为腺苷酸环化酶系统的天然外周膜成分存在，并且可能是催化活性表达和稳定所必需的。
