Kv5.1

Kv5.1 (also known as K8; kH1; KCNF; MGC33316), encoded by the gene KCNF1, is a member of the voltage-gated, subfamily F. Kv5.1 channels cannot generate K+ channel activity by themselves, but modulate in a specific way the function of Kv2.1 and Kv2.2 subunits [400], [399]. NCBI

KCNF1 is intronless and expressed in all tissues tested, including the heart, skeletal muscle, brain, kidney, and pancreas. NCBI

Visual Representation of Kv5.1 Structure
Methodology for visual representation of structure available here

STRUCTURE AND COMPARISON OF HUMAN AND RAT KV5.1

kH1 and Kv5.1 (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 associated 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]

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]

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]

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

Kv2.1

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]

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

Contributors: Rajnish Ranjan, Michael Schartner, Nitin Khanna, Katherine Johnston