Ganapathy V, Leibach F H
J Biol Chem. 1983 Dec 10;258(23):14189-92.
We examined the role of pH gradient and membrane potential in dipeptide transport in purified intestinal and renal brush-border membrane vesicles which were predominantly oriented right-side out. With an intravesicular pH of 7.5, changes in extravesicular pH significantly affected the transport of glycyl-L-proline and L-carnosine, and optimal dipeptide transport occurred at an extravesicular pH of 5.5-6.0 in both intestine and kidney. When the extravesicular pH was 5.5, glycyl-L-proline transport was accelerated 2-fold by the presence of an inward proton gradient. A valinomycin-induced K+ diffusion potential (interior-negative) stimulated glycyl-L-proline transport, and the stimulation was observed in the presence and absence of Na+. A carbonyl cyanide p-trifluoromethoxyphenylhydrazone-induced H+ diffusion potential (interior-positive) reduced dipeptide transport. It is suggested that glycyl-L-proline and proton(s) are cotransported in intestinal and renal brush-border membrane vesicles, and that the process results in a net transfer of positive charge.
我们研究了pH梯度和膜电位在纯化的肠和肾刷状缘膜囊泡中（主要为外翻取向）二肽转运中的作用。囊泡内pH为7.5时，囊泡外pH的变化显著影响甘氨酰-L-脯氨酸和L-肌肽的转运，在肠和肾中，囊泡外pH为5.5 - 6.0时二肽转运最佳。当囊泡外pH为5.5时，内向质子梯度的存在使甘氨酰-L-脯氨酸的转运加速了2倍。缬氨霉素诱导的K⁺扩散电位（内部为负）刺激了甘氨酰-L-脯氨酸的转运，且在有和没有Na⁺的情况下均观察到这种刺激。羰基氰化物对三氟甲氧基苯腙诱导的H⁺扩散电位（内部为正）降低了二肽转运。提示在肠和肾刷状缘膜囊泡中甘氨酰-L-脯氨酸和质子是共转运的，且该过程导致正电荷的净转移。
