Kv5.1

Description: potassium voltage-gated channel, subfamily F, member 1
Gene: Kcnf1 Synonyms: Kv5.1, kcnf1, kh1, ik8, kcnf

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Introduction

The gene KCNF1 encodes Kv5.1, a member of the potassium channel, voltage-gated, subfamily F. Also known as K8; kH1; KCNF; MGC33316. This gene is intronless and expressed in all tissues tested, including the heart, skeletal muscle, brain, kidney, and pancreas.

http://www.ncbi.nlm.nih.gov/gene/3754

The alpha subunits Kv5.1 (IK8) - like Kv6.1 (K13), and Kv8.1 - cannot generate K+ channel activity by themselves, but modulate in a specific way the function of Kv2.1 and Kv2.2 subunits [400], [399].

Experimental data

Rat Kv5.1 gene in CHO host cell datasheet
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Gene

26 genes have been described encoding for different Kv alpha-subunits. These are divided into subfamilies by sequence similarities: within a subfamily members share 70% of sequence identity, whereas between different subfamilies this percentage drops to 40%, reflecting the homology in the core section S1–S6 [650].

RGD ID	Chromosome	Position	Species
631414	6	40910390-40913068	Rat
1621180	12	17178906-17183694	Mouse
735852	2	11052063-11054351	Human

Kcnf1 : potassium voltage-gated channel, subfamily F, member 1

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Transcript

Acc No	Sequence	Length	Source
NM_001169104	n/A	n/A	NCBI
NM_201531	n/A	n/A	NCBI
NM_002236	n/A	n/A	NCBI

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Ontology

Accession		Name			Definition					Evidence
GO:0016020		membrane			Double layer of lipid molecules that encloses all cells, and, in eukaryotes, many organelles; may be a single or double lipid bilayer; also includes associated proteins.					IEA
GO:0008076		voltage-gated potassium channel complex			A protein complex that forms a transmembrane channel through which potassium ions may cross a cell membrane in response to changes in membrane potential.					IEA

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Interaction

Kv2.1

the effects of coexpression of Kv2.1 with electrically silent Kv5.1 or Kv6.1 alpha-subunits in Xenopus oocytes on channel gating. Kv5.1 coexpression alsoslowed deactivation of Kv2.1. In contrast, Kv6.1 was much less effective in speeding inactivation at intermediate potentials, had a slowing effect on inactivation at strong depolarizations, and had no effect on cumulative inactivation

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Protein

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Structure

STRUCTURE AND COMPARISON OF HUMAN AND RAT KV5.1

kH1 and IK8 are completely identical in S3, S4, S5, S6 and H5 domains. This probably underlines the importance of the core region for K/ channel function and it associ- ated properties. At the N-terminal tail, IK8 is 12 amino acid longer than kH1. At the beginning of 5'end, kH1 is followed by a 6 amino acid sequence which is mismatched. At the C-terminal cytoplasmic tail, kH1 and IK8 are distinguished by one gap and ten amino acids which are mismatched [1698]

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Distribution

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Expression

Expression of Kv5.1

kH1 was expressed abundantly in tissues examined, including the heart, skeletal muscle, and less abundant in the brain, liver, kidney, and pancreas [1698]

Northern blot analysis revealed that KH1 was expressed as a 5-kb mRNA in all tissues tested, with the highest levels in heart. A 2.4-kb transcript was detected only in brain (omim.org)

UBSM and mouse brain tissue

T-PCR for voltage-gated K+ channel (KV) subunits revealed the expression of Kv2.1, Kv5.1, Kv6.1, Kv6.2 and Kv6.3 in isolated urinary bladder smooth muscle myocytes as well as mouse brain. A comparison of the biophysical properties of UBSM IK(V) with those reported for Kv2.1 and Kv5.1 and/or Kv6 heteromultimeric channels demonstrated a marked similarity. We propose that heteromultimeric channel complexes composed of Kv2.1 and Kv5.1 and/or Kv6 subunits form the molecular basis of the mouse UBSM IK(V) [1699]

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Functional

Kv5.1 coexpression slowed deactivation of Kv2.1, accelerated the rate of inactivation of Kv2.1 at intermediate potentials (-30 to 0 mV), without affecting the rate at strong depolarization (0 to 40 mV), and markedly accelerated the rate of cumulative inactivation evoked by high-frequency trains of short pulses.[400], [398]

KV5.1 has no function on its own, but has important modulatory actions on KV2 channels [399]

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Kinetics

Kinetic interaction of Kv5.1 and Kv2

Kv5 and Kv6 are members of the electrically silent families that are capable of evoking a large negative shift in the steady-state inactivation of Kv2.1- and Kv2.2-containing channels. The half-maximal steady-state inactivation values reported for these heteromultimeric channels are consistent with the value of −61 mV reported here for the UBSM IK(V). Steady-state activation of the UBSM IK(V) demonstrates a half-maximal value of 1.1 mV, which is mid-range of that reported for Kv2.1 (between 10 mV and −1.7 mV), is more negative than Kv2.1/Kv5.1 (18 mV) and is more positive than Kv2.1/Kv6.1 (-9.4 mV). It seems possible that the half-maximal steady-state activation value of a given heteromultimeric channel will be dependent on the stoichiometry of Kv2.1, Kv5.1 and Kv6.1 channel subunits [1699]

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