Kikuchi K, Ghishan F K
Gastroenterology. 1987 Jul;93(1):106-13. doi: 10.1016/0016-5085(87)90321-0.
The characteristics of phosphate transport across the human intestinal basolateral membrane were determined using an enriched preparation in which uphill Na1+-dependent D-glucose transport could not be demonstrated but adenosine triphosphate-dependent calcium transport was present. The human basolateral membrane vesicles were oriented as follows: 64% inside-out vesicles and 36% rightside-out vesicles or sheets, or both. Phosphate transport showed a 3.4-fold transient "overshoot" phenomena in the presence of an inwardly directed sodium gradient. Computerized Michaelis-Menten kinetics for the net active transport component indicated a Vmax of 65 +/- 5 pmol/mg protein per 8 s and a Km of 93 +/- 15 microM. The transport process was electroneutral. Gramicidin D and transstimulation studies confirmed the presence of a Na+-phosphate carrier at the basolateral membrane. Adenosine triphosphate enhanced phosphate uptake, indicating an adenosine triphosphate-dependent phosphate transport process. These studies are the first to determine the presence of a phosphate carrier in human intestinal basolateral membrane.
利用一种富集制剂确定了磷酸盐跨人肠基底外侧膜转运的特性，在该制剂中无法证明存在依赖于钠离子的上坡D-葡萄糖转运，但存在依赖于三磷酸腺苷的钙转运。人基底外侧膜囊泡的取向如下：64%为内翻囊泡，36%为外翻囊泡或片层，或两者皆有。在存在内向钠梯度的情况下，磷酸盐转运表现出3.4倍的瞬时“超调”现象。对净主动转运成分进行的计算机化米氏动力学分析表明，最大转运速率（Vmax）为每8秒65±5 pmol/mg蛋白质，米氏常数（Km）为93±15 μM。转运过程是电中性的。短杆菌肽D和转刺激研究证实了基底外侧膜存在钠-磷酸盐载体。三磷酸腺苷增强了磷酸盐摄取，表明存在依赖于三磷酸腺苷的磷酸盐转运过程。这些研究首次确定了人肠基底外侧膜中存在磷酸盐载体。
