Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, 2 Place Viala, Montpellier Cedex 2, France.
Cell Mol Life Sci. 2010 Aug;67(15):2511-32. doi: 10.1007/s00018-010-0317-7. Epub 2010 Mar 24.
Bacterial Trk and Ktr, fungal Trk and plant HKT form a family of membrane transporters permeable to K(+) and/or Na(+) and characterized by a common structure probably derived from an ancestral K(+) channel subunit. This transporter family, specific of non-animal cells, displays a large diversity in terms of ionic permeability, affinity and energetic coupling (H(+)-K(+) or Na(+)-K(+) symport, K(+) or Na(+) uniport), which might reflect a high need for adaptation in organisms living in fluctuating or dilute environments. Trk/Ktr/HKT transporters are involved in diverse functions, from K(+) or Na(+) uptake to membrane potential control, adaptation to osmotic or salt stress, or Na(+) recirculation from shoots to roots in plants. Structural analyses of bacterial Ktr point to multimeric structures physically interacting with regulatory subunits. Elucidation of Trk/Ktr/HKT protein structures along with characterization of mutated transporters could highlight functional and evolutionary relationships between ion channels and transporters displaying channel-like features.
细菌 Trk 和 Ktr、真菌 Trk 和植物 HKT 形成了一类可通透 K(+)和/或 Na(+)的膜转运蛋白家族，其特征是具有可能源自于祖先 K(+)通道亚基的共同结构。这种转运蛋白家族是动物细胞所特有的，在离子通透性、亲和力和能量偶联（H(+)-K(+)或 Na(+)-K(+)协同转运、K(+)或 Na(+)单转运）方面表现出很大的多样性，这可能反映了生活在波动或稀释环境中的生物体对适应的高度需求。Trk/Ktr/HKT 转运蛋白参与多种功能，从 K(+)或 Na(+)摄取到膜电位控制，适应渗透或盐胁迫，或植物中从芽到根的 Na(+)再循环。对细菌 Ktr 的结构分析表明，其与调节亚基物理相互作用形成多聚体结构。阐明 Trk/Ktr/HKT 蛋白结构并对突变转运蛋白进行特征分析，可以突出具有通道样特征的离子通道和转运蛋白之间的功能和进化关系。
