Kowalczyk Stanisław, Hetmann Anna
Zakład Biochemii, Instytut Biologii Ogó1nej i Molekularnej, Uniwersytet Mikołaja Kopernika, Toruń.
Postepy Biochem. 2008;54(4):412-22.
The superfamily of G-protein-coupled receptors (GPCRs) is one of the largest and most diverse family of proteins in mammals. Plants, in contrast to animals, have a greatly simplified repertoire of GPCRs. To date, only AtGCR1 and AtRGS1 have been shown to physically interacts with a plant G-protein. Also, the number of G-protein complex components in plants is dramatically less than in other Eukaryotes. Only one prototypical Ga subunit, one Gbeta and two Ggamma subunits have been identified in A. thaliana and rice. Similarly, there are few known downstream effectors that physicaly interact with either the plant Ga subunit or the Gbetagamma dimer. The best-characterized effector is phospholipase D (PLDalpha1). Besides, the potential Galpha effectors are: cupin-domain protein designated as Atpirin1, prephenate dehydratase--a cytosolic enzyme involved in regulation of the shikimate pathway, and THF1 protein located in plastid membranes. Indirect evidences suggest that Galpha may interact with ion channels and phospholipases A2 and C, whereas Gbetagamma dimer supposedly interacts with a Golgi-localized hexose transporter.
G蛋白偶联受体（GPCRs）超家族是哺乳动物中最大且最多样化的蛋白质家族之一。与动物不同，植物的GPCRs种类大大简化。迄今为止，只有拟南芥G蛋白偶联受体1（AtGCR1）和拟南芥G蛋白信号调节蛋白1（AtRGS1）被证明能与植物G蛋白发生物理相互作用。此外，植物中G蛋白复合体成分的数量比其他真核生物要少得多。在拟南芥和水稻中仅鉴定出一个典型的Gα亚基、一个Gβ亚基和两个Gγ亚基。同样，很少有已知的下游效应器能与植物Gα亚基或Gβγ二聚体发生物理相互作用。研究最充分的效应器是磷脂酶D（PLDα1）。此外，潜在的Gα效应器有：被命名为Atpirin1的cupin结构域蛋白、预苯酸脱水酶（一种参与莽草酸途径调控的胞质酶）以及位于质体膜上的THF1蛋白。间接证据表明，Gα可能与离子通道以及磷脂酶A2和C相互作用，而Gβγ二聚体可能与高尔基体定位的己糖转运蛋白相互作用。
