Elgavish A, Wallace R W, Pillion D J, Meezan E
Biochim Biophys Acta. 1984 Oct 17;777(1):1-8. doi: 10.1016/0005-2736(84)90490-5.
Polyamines are natural constituents of most living organisms. However, their function in normal or pathological conditions is not fully understood. We have investigated in vitro effects of polyamines on characteristic properties of isolated renal brush-border membrane vesicles in order to determine whether polyamines have a regulatory role in membrane transport processes. The polyamines putrescine, spermidine and spermine were found to stimulate D-glucose uptake. Diffusional L-glucose uptake was not altered, indicating that the polyamines affected the active transport of D-glucose, rather than inducing nonspecific changes in membrane lipid properties. The amiloride-sensitive Na+ /H + exchange was slightly inhibited by polyamines while Mg2+ -ATPase activity was stimulated. The polyamine effects could not be explained solely by the polycationic properties of these agents, since polycationic polypeptides had an opposite effect. For example, lysozyme was found to inhibit D-glucose transport. Spermine was incorporated into the trichloroacetic acid-insoluble fraction of brush-border membrane proteins. Results indicated that this incorporation process consisted of at least two components: a Ca2+ -independent component and a Ca2+ -dependent component, possibly as a result of transglutaminase activity which was present in the isolated renal brush-border membranes. By using SDS-polyacrylamide gel electrophoresis in conjunction with fluorography, [3H]spermine was shown to be incorporated into several brush-border membrane proteins, mainly the 57 kDa, 74 kDa, 100 kDa, a heavy molecular weight band (greater than 200 kDa) and a low molecular weight band (less than 10 kDa). Our results suggest that the polyamine effects on membrane function may be due to a covalent modification of membrane proteins, possibly via a transglutaminase-mediated incorporation of polyamines or to the crosslinking of membrane proteins.
多胺是大多数生物体的天然成分。然而，它们在正常或病理条件下的功能尚未完全明确。我们研究了多胺对分离的肾刷状缘膜囊泡特性的体外影响，以确定多胺在膜转运过程中是否具有调节作用。发现多胺腐胺、亚精胺和精胺能刺激D-葡萄糖摄取。扩散性L-葡萄糖摄取未改变，这表明多胺影响D-葡萄糖的主动转运，而不是诱导膜脂质特性的非特异性变化。多胺对氨氯地平敏感的Na+/H+交换有轻微抑制作用，而Mg2+-ATP酶活性则受到刺激。这些多胺的作用不能仅由这些物质的聚阳离子特性来解释，因为聚阳离子多肽有相反的作用。例如，发现溶菌酶能抑制D-葡萄糖转运。精胺被整合到刷状缘膜蛋白的三氯乙酸不溶性部分。结果表明，这种整合过程至少由两个成分组成：一个不依赖Ca2+的成分和一个依赖Ca2+的成分，这可能是由于分离的肾刷状缘膜中存在转谷氨酰胺酶活性。通过使用SDS-聚丙烯酰胺凝胶电泳结合荧光自显影，显示[3H]精胺被整合到几种刷状缘膜蛋白中，主要是57 kDa、74 kDa、100 kDa、一条高分子量带（大于200 kDa）和一条低分子量带（小于10 kDa）。我们的结果表明，多胺对膜功能的影响可能是由于膜蛋白的共价修饰，可能是通过转谷氨酰胺酶介导的多胺整合或膜蛋白的交联。
