Verrey François, Closs Ellen I, Wagner Carsten A, Palacin Manuel, Endou Hitoshi, Kanai Yoshikatsu
Institute of Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland,
Pflugers Arch. 2004 Feb;447(5):532-42. doi: 10.1007/s00424-003-1086-z. Epub 2003 Jun 11.
The SLC7 family is divided into two subgroups, the cationic amino acid transporters (the CAT family, SLC7A1-4) and the glycoprotein-associated amino acid transporters (the gpaAT family, SLC7A5-11), also called light chains or catalytic chains of the hetero(di)meric amino acid transporters (HAT). The associated glycoproteins (heavy chains) 4F2hc (CD98) or rBAT (D2, NBAT) form the SLC3 family. Members of the CAT family transport essentially cationic amino acids by facilitated diffusion with differential trans-stimulation by intracellular substrates. In some cells, they may regulate the rate of NO synthesis by controlling the uptake of l-arginine as the substrate for nitric oxide synthase (NOS). The heterodimeric amino acid transporters are, in contrast, quite diverse in terms of substrate selectivity and function (mostly) as obligatory exchangers. Their selectivity ranges from large neutral amino acids (system L) to small neutral amino acids (ala, ser, cys-preferring, system asc), negatively charged amino acid (system x(c)(-)) and cationic amino acids plus neutral amino acids (system y(+)L and b(0,+)-like). Cotransport of Na(+) is observed only for the y(+)L transporters when they carry neutral amino acids. Mutations in b(0,+)-like and y(+)L transporters lead to the hereditary diseases cystinuria and lysinuric protein intolerance (LPI), respectively.
SLC7家族分为两个亚组，即阳离子氨基酸转运体（CAT家族，SLC7A1 - 4）和糖蛋白相关氨基酸转运体（gpaAT家族，SLC7A5 - 11），也被称为异源（二）聚体氨基酸转运体（HAT）的轻链或催化链。相关的糖蛋白（重链）4F2hc（CD98）或rBAT（D2，NBAT）构成SLC3家族。CAT家族成员主要通过易化扩散转运阳离子氨基酸，细胞内底物会产生不同的反式刺激作用。在某些细胞中，它们可能通过控制作为一氧化氮合酶（NOS）底物的L - 精氨酸的摄取来调节NO合成的速率。相比之下，异源二聚体氨基酸转运体在底物选择性和功能方面（大多）作为 obligatory 交换体则相当多样。它们的选择性范围从大中性氨基酸（系统L）到小中性氨基酸（ala、ser、优先摄取cys，系统asc）、带负电荷的氨基酸（系统x(c)(-)）以及阳离子氨基酸加中性氨基酸（系统y(+)L和b(0,+)样）。仅当y(+)L转运体携带中性氨基酸时才会观察到Na(+)的共转运。b(0,+)样和y(+)L转运体的突变分别导致遗传性疾病胱氨酸尿症和赖氨酸尿性蛋白不耐受症（LPI）。 （注：“obligatory”这个词在医学专业语境中可能有特定含义，但在一般语境下较难准确翻译，这里保留英文供参考，可根据具体医学知识进一步准确理解其在文中的意思。）
