RECONSTITUTION OF FUNCTIONAL WATER CHANNELS IN LIPOSOMES CONTAINING PURIFIED RED-CELL CHIP28 PROTEIN
RECONSTITUTION OF FUNCTIONAL WATER CHANNELS IN LIPOSOMES CONTAINING PURIFIED RED-CELL CHIP28 PROTEIN
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DOI：
10.1021/bi00148a002
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发表时间：
1992-08-25
期刊：
影响因子：
2.9
通讯作者：
AGRE, P
中科院分区：
文献类型：
--
作者：
ZEIDEL, ML;AMBUDKAR, SV;AGRE, P
水通过高度特化的通道迅速穿过红细胞和肾小管的质膜。CHIP28是红细胞和肾小管中丰富的整体膜蛋白，注射CHIP28 RNA的非洲爪蟾卵母细胞具有高渗透性，P(f) [Preston et al. (1992) Science 256, 385-387]。从人红细胞中纯化的CHIP28被重组成蛋白脂质体，以确定CHIP28本身是否是水通道的功能单元并表征其生理行为。CHIP28蛋白脂质体的P(f)值是对照脂质体的50倍，但对尿素和质子的通透性没有增加。与完整的红细胞一样，CHIP28蛋白脂体的P(f)被巯基汞试剂可逆地抑制，并表现出低的阿伦尼乌斯活化能。CHIP28介导的水通量大小（每CHIP28 11.7 x 10(-14) cm3/s）对应于完整红细胞的已知P(f)。这些结果表明，CHIP28蛋白作为一个分子水通道，也表明CHIP28负责红细胞中的大多数跨膜水运动。
Water rapidly crosses the plasma membranes of red blood cells (RBCs) and renal tubules through highly specialized channels. CHIP28 is an abundant integral membrane protein in RBCs and renal tubules, and Xenopus laevis oocytes injected with CHIP28 RNA exhibit high osmotic water permeability, P(f) [Preston et al. (1992) Science 256, 385-387]. Purified CHIP28 from human RBCs was reconstituted into proteoliposomes in order to establish if CHIP28 is itself the functional unit of water channels and to characterize its physiological behavior. CHIP28 proteoliposomes exhibit P(f) which is up to 50-fold above that of control liposomes, but permeability to urea and protons is not increased. Like intact RBC, the P(f) of CHIP28 proteoliposomes is reversibly inhibited by mercurial sulfhydryl reagents and exhibits a low Arrhenius activation energy. The magnitude of CHIP28-mediated water flux (11.7 x 10(-14) cm3/s per CHIP28) corresponds to the known P(f) of intact RBCs. These results demonstrate that CHIP28 protein functions as a molecular water channel and also indicate that CHIP28 is responsible for most transmembrane water movement in RBCs.