Molecular cloning of a member of a third class of Shaker-family K+ channel genes in mammals.

McCormack, Tom; Miera, E C Vega-Saenz de; Rudy, Bernardo

doi:10.1073/pnas.87.13.5227

Cited by 70 publications

(35 citation statements)

References 28 publications

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“…4). The K d for block by TEA of Kv3.2 is under 1 mM and that for Kv2.1 is 5.6 mM (28,29). The TEA sensitivity of 0.8 mM observed experimentally in the ␤TC3-neo and rodent ␤-cells could thus be achieved by co-expression of Kv3.2 and 2.1 channels.…”

Section: Resultsmentioning

confidence: 75%

Expression and Function of Pancreatic β-Cell Delayed Rectifier K+ Channels

Roe

Worley

Mittal

et al. 1996

Journal of Biological Chemistry

115

134

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Voltage-dependent delayed rectifier K؉ channels regulate aspects of both stimulus-secretion and excitationcontraction coupling, but assigning specific roles to these channels has proved problematic. Using transgenically derived insulinoma cells (␤TC3-neo) and ␤-cells purified from rodent pancreatic islets of Langerhans, we studied the expression and role of delayed rectifiers in glucose-stimulated insulin secretion.

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Section: Resultsmentioning

confidence: 75%

Expression and Function of Pancreatic β-Cell Delayed Rectifier K+ Channels

Roe

Worley

Mittal

et al. 1996

Journal of Biological Chemistry

115

134

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“…In line with previous reports, Raw 1 and Raw2 channels mediated non-inactivating currents and Raw3 channels fast inactivating, A-type currents ( Figure SA and B). Rawl and Raw2 channels mediated potassium currents which were very similar in their properties to the currents mediated by RKShIIIA, KV3.2b, KV3.2c and by Kv4 and NGK2 channels, respectively (Yokoyama et al, 1989;Luneau et al, 1991a,b;T.McCormack et al, 1990T.McCormack et al, , 1991 (McCormack et al, 1990). However, the Raw conductance curves decline with large depolarizations.…”

Section: Resultsmentioning

confidence: 99%

Characterization of a Shaw-related potassium channel family in rat brain.

et al. 1992

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Previously, we characterized a Shaker-related family of voltage-gated potassium channels (RCK) in rat brain. Now, we describe a second family of voltage-gated potassium channels in the rat nervous system. This family is related to the Drosophila Shaw gene and has been dubbed Raw. In contrast to the RCK potassium channel family the Raw family utilizes extensive alternative splicing for expressing potassium channel subunits with variant C-termini. These alternative C-termini do not appear to influence the electrophysiological and pharmacological properties as studied in the Xenopus oocyte expression system. In situ hybridizations to sections of rat brain indicate that members of the Raw family are expressed in distinct areas of the central nervous system. Probably, Raw channels are expressed predominantly as homomultimers. Immunocytochemical experiments with antibodies against Raw3 and RCK4 proteins which form two distinct A-type potassium channels indicate that in hippocampus the two channels are expressed both in different neurons and in the same ones. In general, properties of Raw potassium channels appeared to be similar to RCK channels. However, Raw outward currents, in contrast to RCK currents, exhibit an intense rectification at test potentials higher than +20 to +40 mV. RCK and Raw channel subunits did not measurably coassemble into RCK/Raw heteromultimers after coinjecting RCK and Raw cRNA into Xenopus oocytes. These results suggest that members of the RCK and the Raw potassium channel families express potassium channels which form independent outward current systems. Combining the results of in situ hybridizations, immunocytochemical staining and expression of the cloned potassium channels in Xenopus oocytes demonstrates that unrestrained mixing of potassium channel subunits to form hybrid channels does not occur in the rat central nervous system. A single neuron is able to express multiple, independently assembled potassium channels.

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“…Subsequently, the Shaker.related K + channel cDNAs Shah, Shaw, and Shal were identified m Drosophila [17]; these code for slowly-or noninactLvating K ~" channels [22], Similar vertebrate K* channel cDNAs were ~denttfied in the mammalian brain, most notably the Shaker.ranted RCK g ÷ channel family in rat brain [5], Expression of RCK cRNA in Xenopus oocytes produces several types of voltage.gated K* channels, of both the delayed rectifier (slowly-reactivating) or A-type (rapidly.inactivating). Members of the Shaw-related K* channel family m rat brain also resemble delayed-rectifler type K + channels (NGK2, RKShlIIA) [4,18] or A-type K ÷ channels (Raw3). These observations suggest that A-type and delayed-rectifier K + channels were both drayed from a prototype voltage-gated K" channel and that within a g=ven K" channel family small sequence varlatmns obviously suffice to convert an A-type K ~ channel into a delayed rectifier type K" channel.…”

Section: Discussionmentioning

confidence: 99%

Cloning and functional expression of a TEA‐sensitive A‐type potassium channel from rat brain

et al. 1991

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) Afax. Plmtck.htxr#ut fiTr mrdt:htl~rh¢ For~rhung. Juht~trajJ¢ 29, dgO0 Heht¢lbcr~, Germmu" and J Ruhr Univers~tdt B.rhmn, Lrhrzttthl fiir lhoeheml¢, .I630 gotham, r;¢rmanv R¢ceiwd 2? Novcmbw 1990A rat brain eDNA (Raw.l} related to the Dra.fophga Sha. K= channel l'Amlly has been character)xed, Raw3 cRNA leads to the formation of TEA. in~nsltt,,'¢, ras! inactivating (A-tyI~) K' ,:hannels whefl )njecled into ,Wnapus laevl~ o¢¢ytes Raw3 ch{tnnels have markedly different prolztrttes from the prcv)ously cloned rat A,|yp¢ K" channel RCK4, Raw3 channels ol~rate m the positive voltztge range MATERIALS AND METHODSA rat cortex eDNA library (a gift from P Seeburg, Heidelberg) has been screened w=th a )=P labelled NGK2 [18] eDNA probe under con. ehtionsoflow stringency[6, 171 TwoovcrlappmgcDNAswer¢isolated and sequenced (7,8] The combined eDNA sequence ~as 2858 bp long The composite raw3 cDNA was cloned into tile expression see tot pAS2, Th~s vector was constructed of Bluescrlpt KS" (Stratagene) and pAKSI8 Xenopus/news oocytes were rejected wsth cRNA and incubated for 2-3 days at 19*C [10] The kmeuc properties of Raw3 channels were determined from macro.patch recordings lit] in the cell-attacl~cd conhguratlon of the patch clamp technique I'h¢ pharmacologtcal profile was estabhsl~ed ushtg a conventional two.mlcroelectrode voltage-clamp Microelectrodes were filled with I M KCI and had a resistance of 200-500 k.q Single channels were recorded m the cellattached configuratton All experiments were done at 20°C m normal frog Rnlger solution of the following composltmn (m raM) NaCI I IS, KCI2, CaCl= 1 8, Hepes 10, pH 7 2 In some exper,mentssodlum wa~ replaced by 4-AP or TEA (Sigma) or DTX (gift from Dr F, Dreyer, Glessen, Germany) was added Patch p~pettes were filled with normal frog Ringer solutmn Leak and capacitive currents were subtracted digitally using the P/4 method [12] 3. RESULTS Prtmary sequence of raw3 K ÷ channel proteinTwo overlapping cDNAs, encoding Raw3, were isolated from a rat cortex ~.DNA hbrary. The longest open reading frame corresponds to an amino aczd sequence of 625 residues (Fig. 1). The hydropathy analysis [13] Pubhshed bb ElsevJer S.tence Pubhshers B V fBtamedwal Dwtswn) 21 1

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Molecular cloning of a member of a third class of Shaker-family K+ channel genes in mammals.

Cited by 70 publications

References 28 publications

Expression and Function of Pancreatic β-Cell Delayed Rectifier K+ Channels

Expression and Function of Pancreatic β-Cell Delayed Rectifier K+ Channels

Characterization of a Shaw-related potassium channel family in rat brain.

Cloning and functional expression of a TEA‐sensitive A‐type potassium channel from rat brain

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