Ahrens Jörg, Leuwer Martin, Stachura Sina, Krampfl Klaus, Belelli Delia, Lambert Jeremy J, Haeseler Gertrud
Department of Anesthesiology, OE 8050, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
Anesth Analg. 2008 Dec;107(6):1875-83. doi: 10.1213/ane.0b013e3181875a31.
Propofol, well known for its anesthetic effects, acts as a positive allosteric modulator of the alpha-aminobutyric acid type A (GABA(A)) receptor but also enhances the function of the glycine receptor. The GABA modulatory effects of propofol are influenced by an amino acid residue located within the second transmembrane domain (TM2) of the GABA(A) receptor beta subunit. In glycine alpha(1) subunits, the homologous residue (serine 267) affects the glycine modulatory actions of alcohols and alkane anesthetics. In the present study we investigated the role of this residue on the interaction of propofol with the glycine alpha(1) and alpha(1)beta receptor.
The influence of propofol on wild type and mutant (alpha(1)S267M, alpha(1)S267I, alpha(1)S267Mbeta, alpha(1)S267Ibeta) glycine receptors expressed in human embryonic kidney 293 cells was investigated by using the whole-cell clamp technique.
Mutation of the alpha(1) subunit TM2 serine residue to either isoleucine or methionine decreased the sensitivity of the receptor to glycine, and abolished the direct activation of the glycine receptor by propofol. Additionally, the methionine and particularly the isoleucine mutation decreased the glycine-enhancing actions of propofol.
The nature of the TM2 residue (267) of the glycine alpha(1) subunit influences the glycine modulatory effect of propofol and direct activation of the receptor by this anesthetic. A comparison of the impact of such complementary mutations on the interaction of propofol with glycine and GABA(A) receptors should permit a better understanding of the molecular determinants of action of propofol on these structurally related receptors and may aid in the development of selective glycine receptor modulators.
丙泊酚以其麻醉作用而闻名，它作为γ-氨基丁酸A型（GABA(A)）受体的正变构调节剂，同时也增强甘氨酸受体的功能。丙泊酚对GABA的调节作用受GABA(A)受体β亚基第二个跨膜结构域（TM2）内的一个氨基酸残基影响。在甘氨酸α(1)亚基中，同源残基（丝氨酸267）影响醇类和烷烃麻醉剂对甘氨酸的调节作用。在本研究中，我们调查了该残基在丙泊酚与甘氨酸α(1)及α(1)β受体相互作用中的作用。
采用全细胞膜片钳技术，研究丙泊酚对在人胚肾293细胞中表达的野生型和突变型（α(1)S267M、α(1)S267I、α(1)S267Mβ、α(1)S267Iβ）甘氨酸受体的影响。
将α(1)亚基TM2丝氨酸残基突变为异亮氨酸或甲硫氨酸会降低受体对甘氨酸的敏感性，并消除丙泊酚对甘氨酸受体的直接激活作用。此外，甲硫氨酸突变尤其是异亮氨酸突变会降低丙泊酚增强甘氨酸的作用。
甘氨酸α(1)亚基TM2残基（267）的性质影响丙泊酚对甘氨酸的调节作用以及该麻醉剂对受体的直接激活作用。比较此类互补突变对丙泊酚与甘氨酸及GABA(A)受体相互作用的影响，应有助于更好地理解丙泊酚对这些结构相关受体作用的分子决定因素，并可能有助于开发选择性甘氨酸受体调节剂。
