Halide permeation in wild-type and mutant cystic fibrosis transmembrane conductance regulator chloride channels

被引:97
作者
Tabcharani, JA [1 ]
Linsdell, P [1 ]
Hanrahan, JW [1 ]
机构
[1] MCGILL UNIV, DEPT PHYSIOL, MONTREAL, PQ H3G 1Y6, CANADA
关键词
iodide permeability; lyotropic sequence;
D O I
10.1085/jgp.110.4.341
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Permeation of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels by halide ions was studied in stably transfected Chinese hamster ovary cells by using the patch clamp technique. In cell-attached patches with a high Cl- pipette solution, the CFTR channel displayed outwardly rectifying currents and had a conductance near-the membrane potential of 6.0 pS at 22 degrees C or 8.7 pS at 37 degrees C. The current-voltage relationship became linear when patches were excised into symmetrical, N-tris(hydroxymethyl)methyl-2-aminomethane sulfonate (TES)-buffered solutions. Under these conditions, conductance increased from 7.0 PS at 22 degrees C to 10.9 pS at 37 degrees C. The conductance at 22 degrees C was similar to 1.0 pS higher when TES and HEPES were omitted from the solution, suggesting weak, voltage-independent block by pH buffers. The relationship between conductance and Cl- activity was hyperbolic and well fitted by a Michaelis-Menten-type) function having a K-m of similar to 38 mM and maximum conductance of 10 pS at 22 degrees C. Dilution potentials measured with NaCl gradients indicated high anion selectivity (P-Na/P-Cl = 0.003-0.028). Biionic reversal potentials measured immediately after exposure of the cytoplasmic side to various test anions indicated P, (1.8) > P-Br (1.3) > P-Cl (1.0) > P-F (0.17), consistent with a ''weak field strength'' selectivity site. The same sequence was obtained for external halides, although inward F- flow was not observed. Iodide currents were protocol dependent and became blocked after 1-2 min. This coincided with a large shift in the (extrapolated) reversal potential to values indicating a greatly reduced I-/Cl- permeability ratio (P-I/P-Cl < 0.4). The switch to lo iv I- permeability was enhanced at potentials that favored Cl- entry into the pore and was not observed in the R347D mutant, which is thought to lack an anion binding site involved in multi-ion pore behavior. Interactions between Cl- and I- ions may influence I- permeation and be responsible for the wide range of P-I/P-Cl ratios that have been reported for the CFTR channel. The low P-I/P-Cl ratio usually reported for CFTR only occurred after entry into an altered permeability state and thus may not be comparable with permeability ratios for other anions, which are obtained in the absence of iodide. We propose that CFTR displays a ''weak field strength'' anion selectivity sequence.
引用
收藏
页码:341 / 354
页数:14
相关论文
共 64 条
  • [31] INHIBITION OF AN OUTWARDLY RECTIFYING ANION CHANNEL BY HEPES AND RELATED BUFFERS
    HANRAHAN, JW
    TABCHARANI, JA
    [J]. JOURNAL OF MEMBRANE BIOLOGY, 1990, 116 (01) : 65 - 77
  • [32] CFTR CHANNELS IN IMMORTALIZED HUMAN AIRWAY CELLS
    HAWS, C
    KROUSE, ME
    XIA, YF
    GRUENERT, DC
    WINE, JJ
    [J]. AMERICAN JOURNAL OF PHYSIOLOGY, 1992, 263 (06): : L692 - L707
  • [33] Hofmeister F., 1888, ARCH F R EXP PATHOL, V24, P247, DOI DOI 10.1007/BF01918191
  • [34] EXPRESSION OF THE CYSTIC-FIBROSIS GENE IN NONEPITHELIAL INVERTEBRATE CELLS PRODUCES A REGULATED ANION CONDUCTANCE
    KARTNER, N
    HANRAHAN, JW
    JENSEN, TJ
    NAISMITH, AL
    SUN, SZ
    ACKERLEY, CA
    REYES, EF
    TSUI, LC
    ROMMENS, JM
    BEAR, CE
    RIORDAN, JR
    [J]. CELL, 1991, 64 (04) : 681 - 691
  • [35] CALCIUM IS NOT INVOLVED IN THE CAMP-MEDIATED STIMULATION OF CL- CONDUCTANCE IN THE EPICAL MEMBRANE OF NECTURUS GALLBLADDER EPITHELIUM
    KOTTRA, G
    [J]. PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1995, 429 (05): : 647 - 658
  • [36] ELECTRICAL PROPERTIES OF BIMOLECULAR PHOSPHOLIPID MEMBRANES
    LAUGER, P
    LESSLAUER, W
    MARTI, E
    RICHTER, J
    [J]. BIOCHIMICA ET BIOPHYSICA ACTA, 1967, 135 (01) : 20 - +
  • [37] Flickery block of single CFTR chloride channels by intracellular anions and osmolytes
    Linsdell, P
    Hanrahan, JW
    [J]. AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY, 1996, 271 (02): : C628 - C634
  • [38] Multi-ion mechanism for ion permeation and block in the cystic fibrosis transmembrane conductance regulator chloride channel
    Linsdell, P
    Tabcharani, JA
    Hanrahan, JW
    [J]. JOURNAL OF GENERAL PHYSIOLOGY, 1997, 110 (04) : 365 - 377
  • [39] Permeability of wild-type and mutant cystic fibrosis transmembrane conductance regulator chloride channels to polyatomic anions
    Linsdell, P
    Tabcharani, JA
    Rommens, JM
    Hou, YX
    Chang, XB
    Tsui, LC
    Riordan, JR
    Hanrahan, JW
    [J]. JOURNAL OF GENERAL PHYSIOLOGY, 1997, 110 (04) : 355 - 364
  • [40] Disulphonic stilbene block of cystic fibrosis transmembrane conductance regulator Cl- channels expressed in a mammalian cell line and its regulation by a critical pore residue
    Linsdell, P
    Hanrahan, JW
    [J]. JOURNAL OF PHYSIOLOGY-LONDON, 1996, 496 (03): : 687 - 693