Cloning and characterization of maxi K+ channel α-subunit in rabbit kidney.

We have identified in rabbit renal cells two alternatively spliced transcripts of the α-subunit rbslo1 and rbslo2. Rbslo1 has a novel "in-frame" 174-bp insertion immediately after the predicted S8 transmembrane segment, whereas rbslo2 has a 104-bp deletion between S9 and S10, creating a frameshift and a premature termination codon. Amino acid identity between mouse maxi K+ channel α-subunit ( mslo) and rbslo1 was 99%. Two transcript sizes of 4.2 and 7.5 kb were detected in brain, kidney, stomach, testis, and lung. Rbslo is expressed in glomeruli, thin limbs of Henle's loop, medullary and cortical thick ascending limbs of Henle's loop, and cortical, outer, and inner medullary collecting ducts; however, it was rarely detected in proximal convoluted tubules. Rbslo1 is most abundant in inner medulla. Expressed in Xenopus oocytes, rbslo1 generates depolarization-activated, outwardly rectifying K+ currents. Rbslo1 expressed in Chinese hamster ovary cells could be activated by depolarization and Ca2+. These data suggest that rbslo transcripts are expressed in multiple nephron segments and that the magnitude of mRNA expression varies among different nephron segments.

[1]  L. Salkoff,et al.  A human calcium-activated potassium channel gene expressed in vascular smooth muscle. , 1995, The American journal of physiology.

[2]  É. Rousseau,et al.  PKG-I alpha phosphorylates the alpha-subunit and upregulates reconstituted GKCa channels from tracheal smooth muscle. , 1995, The American journal of physiology.

[3]  G. Morley,et al.  Effect of basolateral or apical hyposmolarity on apical maxi K channels of everted rat collecting tubule. , 1995, The American journal of physiology.

[4]  D. Clapham,et al.  The G-protein-gated atrial K+ channel IKAch is a heteromultimer of two inwardly rectifying K+-channel proteins , 1995, Nature.

[5]  L. Pallanck,et al.  Functional role of the β subunit of high conductance calcium-activated potassium channels , 1995, Neuron.

[6]  J. Tseng-Crank,et al.  Cloning, expression, and distribution of functionally distinct Ca2+-activated K+ channel isoforms from human brain , 1994, Neuron.

[7]  J. Stockand,et al.  Large Ca(2+)-activated K+ channels responsive to angiotensin II in cultured human mesangial cells. , 1994, The American journal of physiology.

[8]  L. Salkoff,et al.  Calcium sensitivity of BK-type KCa channels determined by a separable domain , 1994, Neuron.

[9]  R. North,et al.  Functional differences among alternatively spliced variants of Slowpoke, a Drosophila calcium-activated potassium channel. , 1994, The Journal of biological chemistry.

[10]  M. Garcia-Calvo,et al.  Primary sequence and immunological characterization of beta-subunit of high conductance Ca(2+)-activated K+ channel from smooth muscle. , 1994, The Journal of biological chemistry.

[11]  F. Lang,et al.  Effects of [Ca2+]i and temperature on minK channels expressed in Xenopus oocytes , 1993, FEBS letters.

[12]  L. Salkoff,et al.  mSlo, a complex mouse gene encoding "maxi" calcium-activated potassium channels. , 1993, Science.

[13]  R. North,et al.  Calcium-activated potassium channels expressed from cloned complementary DNAs , 1992, Neuron.

[14]  R. Latorre,et al.  Mode of action of iberiotoxin, a potent blocker of the large conductance Ca(2+)-activated K+ channel. , 1992, Biophysical journal.

[15]  M. Tauc,et al.  Apical membrane ionic channels in the rabbit cortical thick ascending limb in primary culture. , 1991, Biochimica et biophysica acta.

[16]  B. Martin,et al.  RT-PCR microlocalization of mRNA for guanylyl cyclase-coupled ANF receptor in rat kidney. , 1991, The American journal of physiology.

[17]  J. Pácha,et al.  Apical maxi K channels in intercalated cells of CCT. , 1991, The American journal of physiology.

[18]  D. Eaton,et al.  Potassium permeable channels in primary cultures of rabbit cortical collecting tubule. , 1991, Kidney international.

[19]  G. Giebisch,et al.  A Ca-activated K channel from rabbit renal brush-border membrane vesicles in planar lipid bilayers. , 1991, The American journal of physiology.

[20]  C. Montrose‐Rafizadeh,et al.  Role of intracellular calcium in volume regulation by rabbit medullary thick ascending limb cells. , 1991, The American journal of physiology.

[21]  K. Kawahara,et al.  Hyposmotic activation of Ca-activated K channels in cultured rabbit kidney proximal tubule cells. , 1991, The American journal of physiology.

[22]  W. Guggino,et al.  Ca2(+)-activated K+ channels from rabbit kidney medullary thick ascending limb cells expressed in Xenopus oocytes. , 1990, The Journal of biological chemistry.

[23]  A. Takai,et al.  Regulation of Ca2+ -dependent K+ -channel activity in tracheal myocytes by phosphorylation , 1989, Nature.

[24]  W. Guggino,et al.  Membrane stretch: a physiological stimulator of Ca2+-activated K+ channels in thick ascending limb. , 1989, The American journal of physiology.

[25]  M. Tauc,et al.  Two types of K+ channels in the apical membrane of rabbit proximal tubule in primary culture. , 1989, Biochimica et biophysica acta.

[26]  S. Nakanishi,et al.  Cloning of a membrane protein that induces a slow voltage-gated potassium current. , 1988, Science.

[27]  B. Alger,et al.  Protein kinase C activators block specific calcium and potassium current components in isolated hippocampal neurons , 1988, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[28]  W. Guggino,et al.  Blocking agents of Ca2+-activated K+ channels in cultured medullary thick ascending limb cells. , 1987, The American journal of physiology.

[29]  W. Guggino,et al.  Forskolin and antidiuretic hormone stimulate a Ca2+-activated K+ channel in cultured kidney cells. , 1985, The American journal of physiology.

[30]  M. Burg,et al.  Differentiated function in cultured epithelia derived from thick ascending limbs. , 1982, The American journal of physiology.