Reeve J, Woo P M
Immunology. 1982 Aug;46(4):859-66.
A steady state algebraic Mass Action analysis of the factors controlling the concentration of the alternative pathway C3 convertase is presented. The positive feedback loop does not make this portion of the complement system insensitive to variation in control protein concentrations; on the contrary, a hyperbolic relationship is revealed between C3 convertase and a complex product of the control protein concentrations which contains some mathematical non-linearities. The consequences of this relationship are explored. It is found that variations in the concentration of any one control protein will have an effect which can only be predicted if its initial concentration and those of the other control proteins are known. The system is capable of responding with a considerable range of amplitudes to a given signal which raises the question as to whether the feedback loop confers biological advantage, not only by augmenting the activation of C3 to C3b, but through its potential for flexibility in responding to an activating stimulus. The analysis may also prove useful in the design and evaluation of experiments to determine the reaction rate constants governing the interactions between the control proteins in the fluid phase in vitro.
本文对控制替代途径C3转化酶浓度的因素进行了稳态代数质量作用分析。正反馈回路并未使补体系统的这一部分对调节蛋白浓度的变化不敏感；相反，C3转化酶与调节蛋白浓度的复合产物之间呈现出一种双曲线关系，其中包含一些数学非线性。探讨了这种关系的后果。研究发现，任何一种调节蛋白浓度的变化所产生的影响，只有在其初始浓度以及其他调节蛋白的浓度已知时才能预测。该系统能够对给定信号做出相当大范围的幅度响应，这就引发了一个问题，即反馈回路是否不仅通过增强C3向C3b的激活，还通过其对激活刺激做出灵活响应的潜力，赋予了生物学优势。该分析在设计和评估实验以确定体外液相中调节蛋白之间相互作用的反应速率常数方面可能也很有用。
