猪组织中α-三磷酸肌醇（肌醇1,2,6-三磷酸）的结合位点；与Ins(1,4,5)P3和Ins(1,3,4,5)P4结合位点的比较。

Binding sites for alpha-trinositol (inositol 1,2,6-trisphosphate) in porcine tissues; comparison with Ins(1,4,5)P3 and Ins(1,3,4,5)P4-binding sites.

作者信息

Stricker R, Westerberg E, Reiser G

机构信息

Institut für Neurobiochemie, Universität Magdeburg, Germany.

出版信息

Br J Pharmacol. 1996 Mar;117(5):919-25. doi: 10.1111/j.1476-5381.1996.tb15281.x.

DOI:10.1111/j.1476-5381.1996.tb15281.x

PMID:8851511

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1909411/

Abstract

The molecular mechanism of action of the inositol trisphosphate isomer, alpha-trinositol (Ins(1,2,6)P3) which has potential therapeutic use in treatment of inflammation and burn oedema, is still unclear. Therefore we have studied binding sites for alpha-trinositol in different tissues. 2. In membranes from pig cerebellum, liver, kidney, heart, and spleen, the density of specific [3]-alpha-trinositol binding sites was maximal at pH 5.0. Cerebellum and spleen showed only one binding site (cerebellum KD = 9.1 microM, spleen KD = 7.3 microM). In the other tissues, there were a high-affinity site (heart KD = 70 nM, liver KD = 790 nM and kidney KD = 1800 nM), besides a low-affinity site with a KD ranging between 32 and 120 microM. In cerebellar membranes, the affinity and density (107 pmol mg-1 protein) of alpha-trinositol binding sites were not affected by phosphate (0 to 25 mM). 3. Binding of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 to membranes from different porcine tissues was also determined. Ins(1,3,4,5)P4, the isomer stereochemically related to alpha-trinositol, binds with an affinity of 1.2 nM in cerebellum, but in the other tissues the binding site density was too low to determine the affinity. With cerebellar membranes heterologous displacement of [3H]-Ins(1,3,4,5)P4 by alpha-trinositol yielded a K1 of 11 microM. The Ins(1,4,5)P3 receptor displayed an affinity of 15 nM in cerebellum and of 5 to 7 nM in the other tissues investigated. 4. The solubilized Ins(1,3,4,5)P4 receptor preparation from cerebellum did not show Ins(1,2,6)P3 binding. Ins(1,2,6)P3 binding was found in the pellet obtained after solubilization of the membranes with the detergent Brij 58. 5. Thus, in different tissues alpha-trinositol binds to proteins with different affinity. They are obviously not related to binding sites for Ins (1,4,5)P3 or for Ins(1,3,4,5)P4. Future experiments have to unravel the identity of the binding protein(s) for alpha-trinositol.

摘要

肌醇三磷酸异构体α-三磷酸肌醇（Ins(1,2,6)P3）在治疗炎症和烧伤水肿方面具有潜在治疗用途，但其分子作用机制仍不清楚。因此，我们研究了α-三磷酸肌醇在不同组织中的结合位点。2. 在猪小脑、肝脏、肾脏、心脏和脾脏的膜中，特异性[3]-α-三磷酸肌醇结合位点的密度在pH 5.0时最大。小脑和脾脏仅显示一个结合位点（小脑KD = 9.1微摩尔，脾脏KD = 7.3微摩尔）。在其他组织中，除了KD在32至120微摩尔之间的低亲和力位点外，还有一个高亲和力位点（心脏KD = 70纳摩尔，肝脏KD = 790纳摩尔，肾脏KD = 1800纳摩尔）。在小脑膜中，α-三磷酸肌醇结合位点的亲和力和密度（107皮摩尔毫克-1蛋白质）不受磷酸盐（0至25毫摩尔）的影响。3. 还测定了Ins(1,4,5)P3和Ins(1,3,4,5)P4与不同猪组织膜的结合。Ins(1,3,4,5)P4是与α-三磷酸肌醇立体化学相关的异构体，在小脑中的结合亲和力为1.2纳摩尔，但在其他组织中，结合位点密度过低，无法确定亲和力。对于小脑膜，α-三磷酸肌醇对[3H]-Ins(1,3,4,5)P4的异源置换产生的K1为11微摩尔。Ins(1,4,5)P3受体在小脑中的亲和力为15纳摩尔，在其他研究组织中的亲和力为5至7纳摩尔。4. 从小脑制备的可溶性Ins(1,3,4,5)P4受体制剂未显示Ins(1,2,6)P3结合。在用去污剂Brij 58溶解膜后获得的沉淀中发现了Ins(1,2,6)P3结合。5. 因此，在不同组织中，α-三磷酸肌醇以不同亲和力与蛋白质结合。它们显然与Ins(1,4,5)P3或Ins(1,3,4,5)P4的结合位点无关。未来的实验必须揭示α-三磷酸肌醇结合蛋白的身份。