Sutter A, Riopelle R J, Harris-Warrick R M, Shooter E M
Prog Clin Biol Res. 1979;31:659-67.
Chick embryonic sensory ganglia cells have two specific nerve growth factor receptors, site I and site II receptors, whose binding affinities differ by two orders of magnitude. As judged by both steady state binding and kinetic data, the two receptors behave independently. The rate of dissociation of the labeled nerve growth factor from site I receptors is increased in the presence of unlabeled nerve growth factor even when its concentration is below that of the labeled growth factor used to equilibrate the cells, a phenomenon which cannot be explained by negative cooperativity. Site I receptors are present only on neurons while site II receptors are present on both neurons and nonneuronal cells. At the concentration of nerve growth factor which produces half maximal stimulation of neurite outgrowth 8% of site I and 0.1% of site II receptors are occupied. This occupancy of site II receptors falls to about 0.01% with bisdesarginine beta nerve growth factor, a derivative which is as biologically active as the unmodified factor but which binds with lower affinity to site II receptors. These data support the idea that interaction of nerve growth factor with site I receptors is responsible for the initiation of neurite outgrowth.
鸡胚感觉神经节细胞有两种特定的神经生长因子受体，即位点I受体和位点II受体，它们的结合亲和力相差两个数量级。从稳态结合和动力学数据判断，这两种受体的行为是独立的。即使未标记的神经生长因子浓度低于用于平衡细胞的标记生长因子的浓度，在其存在下，标记的神经生长因子从位点I受体上的解离速率仍会增加，这种现象无法用负协同性来解释。位点I受体仅存在于神经元上，而位点II受体则存在于神经元和非神经元细胞上。在产生最大神经突生长刺激一半的神经生长因子浓度下，8%的位点I受体和0.1%的位点II受体被占据。用双去精氨酸β神经生长因子处理后，位点II受体的占据率降至约0.01%，双去精氨酸β神经生长因子是一种衍生物，其生物活性与未修饰的因子相同，但与位点II受体的结合亲和力较低。这些数据支持这样一种观点，即神经生长因子与位点I受体的相互作用是神经突生长起始的原因。
