大鼠胃底腺黏膜中胃泌素与其受体相互作用的特征分析。

Characterization of the interaction between gastrin and its receptor in rat oxyntic gland mucosa.

作者信息

Speir G R, Takeuchi K, Johnson L R

出版信息

Biochim Biophys Acta. 1982 Jun 16;716(3):308-15. doi: 10.1016/0304-4165(82)90021-6.

Abstract

A gastrin receptor, identified in crude membrane preparations of rat oxyntic gland mucosa, has an equilibrium dissociation constant (Kd) of approx. 4 . 10(-10)M and a binding capacity of 4 fmol/mg protein. The binding capacity was significantly lower after 2 days of fasting, parallel with a significant drop in serum gastrin levels; there was no change in Kd. In order to verify Scatchard analysis and to determine if there was a coincident alteration in the association (k+1) and dissociation (k-1) rates in the fasted rat, a kinetics study was performed. Under our conditions, there appeared to be a single set of binding sites and the binding reaction obeyed first-order dissociation, and second-order association rate kinetics. Second-order association rate kinetics were validated by demonstrating the independence of the rate constants when there were alterations in the concentrations of reactants. The average k+1 was determined to be 2 . 10(6) M-1 . s-1. The average k-1 was determined to be 1 . 10(-3) s-1. There was no significant change in the k+1 and k-1 in fed and fasted rats. Fasting decreased the number of gastrin receptors without altering the affinity of the receptor for the hormone.

摘要

在大鼠胃底腺黏膜的粗制膜制剂中鉴定出的胃泌素受体，其平衡解离常数（Kd）约为4×10⁻¹⁰M，结合容量为4 fmol/mg蛋白质。禁食2天后，结合容量显著降低，同时血清胃泌素水平显著下降；Kd没有变化。为了验证Scatchard分析，并确定禁食大鼠的结合速率（k+1）和解离速率（k-1）是否同时发生改变，进行了一项动力学研究。在我们的实验条件下，似乎存在一组单一的结合位点，结合反应符合一级解离和二级结合速率动力学。通过证明反应物浓度改变时速率常数的独立性，验证了二级结合速率动力学。测定平均k+1为2×10⁶M⁻¹·s⁻¹。测定平均k-1为1×10⁻³s⁻¹。喂食和禁食大鼠的k+1和k-1没有显著变化。禁食减少了胃泌素受体的数量，但没有改变受体对该激素的亲和力。