| RRC ID |
11731
|
| 著者 |
Ishii TM, Takano M, Xie LH, Noma A, Ohmori H.
|
| タイトル |
Molecular characterization of the hyperpolarization-activated cation channel in rabbit heart sinoatrial node.
|
| ジャーナル |
J Biol Chem
|
| Abstract |
We cloned a cDNA (HAC4) that encodes the hyperpolarization-activated cation channel (If or Ih) by screening a rabbit sinoatrial (SA) node cDNA library using a fragment of rat brain If cDNA. HAC4 is composed of 1150 amino acid residues, and its cytoplasmic N- and C-terminal regions are longer than those of HAC1-3. The transmembrane region of HAC4 was most homologous to partially cloned mouse If BCNG-3 (96%), whereas the C-terminal region of HAC4 showed low homology to all HAC family members so far cloned. Northern blotting revealed that HAC4 mRNA was the most highly expressed in the SA node among the rabbit cardiac tissues examined. The electrophysiological properties of HAC4 were examined using the whole cell patch-clamp technique. In COS-7 cells transfected with HAC4 cDNA, hyperpolarizing voltage steps activated slowly developing inward currents. The half-maximal activation was obtained at -87.2 +/- 2.8 mV under control conditions and at -64.4 +/- 2.6 mV in the presence of intracellular 0.3 mM cAMP. The reversal potential was -34.2 +/- 0.9 mV in 140 mM Na+o and 5 mM K+o versus 10 mM Na+i and 145 mM K+i. These results indicate that HAC4 forms If in rabbit heart SA node.
|
| 巻・号 |
274(18)
|
| ページ |
12835-9
|
| 公開日 |
1999-4-30
|
| DOI |
10.1074/jbc.274.18.12835
|
| PII |
S0021-9258(19)73425-5
|
| PMID |
10212270
|
| MeSH |
Amino Acid Sequence
Animals
Base Sequence
COS Cells
Cloning, Molecular
Cyclic Nucleotide-Gated Cation Channels
DNA, Complementary
Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
Ion Channel Gating
Ion Channels / genetics*
Ion Channels / physiology
Membrane Potentials*
Mice
Molecular Sequence Data
Nerve Tissue Proteins*
Potassium Channels
RNA, Messenger / genetics
RNA, Messenger / metabolism
Rabbits
Sequence Homology, Amino Acid
Sinoatrial Node / metabolism*
|
| IF |
5.108
|
| リソース情報 |
| ヒト・動物細胞 |
COS-7(RCB0539) |
