Kcna3

Potassium voltage-gated channel subfamily A member 3 (MK3) (Voltage-gated potassium channel subunit Kv1.3)

Spatial tier: RESTRICTED · Class: ION_CHANNEL · Top region: PBG (Parabigeminal nucleus) · Positive regions: 24/554

42.2Discovery Score

33.2Targetability Score

CEvidence grade C

What this means: Kcna3: fine CCF profile is restricted toward PBG (top regions: PBG, B, PVT, SAG, ILA2/3; 24 positive regions); direct spatial validation is still required.

Function in PBG: evidence, prediction, innovation

Gene function

Kcna3 encodes Kv1.3, an intronless Shaker-family delayed-rectifier potassium channel. In neurons it sets resting potential, spike repolarisation and firing frequency and is strongly modulated by receptor tyrosine kinase phosphorylation and scaffolding proteins; in lymphocytes and microglia it controls calcium signalling and activation.

Region function

The parabigeminal nucleus is the mammalian nucleus isthmi: spontaneously active cholinergic and glutamatergic neurons reciprocally wired with superior colliculus and projecting to central amygdala, supporting visual attention and looming-evoked freezing and escape.

Published in this region

inferred No region-specific literature found. The closest evidence is that Kv1.3 shapes excitability in other tonically, precisely firing neurons: Gazula et al. 2010 localised Kv1.3 to presynaptic calyx of Held terminals in auditory brainstem MNTB along a tonotopic gradient, and Fadool et al. 2004 showed Kv1.3 deletion transforms olfactory bulb mitral cell currents and produces super-smeller mice. Goddard et al. 2007 characterised PBG pacemaking as I(A)-dependent without identifying the subunit.

Predicted function

Prediction: Kv1.3 is a strong candidate to carry part of the A-type and delayed-rectifier current pacing PBG cholinergic neurons, and to sit in their superficial-SC terminals limiting acetylcholine release per spike. Kcna3 deletion or margatoxin/PAP-1 block should depolarise these neurons, raise spontaneous firing and increase cholinergic facilitation of collicular inhibition, predicting altered looming sensitivity and faster escape. A microglial contribution must be excluded with conditional alleles.

Innovation

★★★★☆ 4/5 Kv1.3 physiology is well worked out in olfactory bulb and immune cells but never examined in isthmic circuits, where its pacemaking role is directly testable.

Tools

Selective blockers margatoxin, ShK-186/dalazatide and other ShK analogues, plus small molecule PAP-1; Kcna3-null mice (Fadool et al. 2004) and conditional alleles; Kv1.3 antibodies validated in brainstem; PBG cholinergic targeting with ChAT-IRES-Cre (JAX 006410).

References

Direct evidence located at the region

Kcna3 Allen ISH at the CCF centroid of PBG

Allen ISH experiment 70723477, section image 70661839 (section 150): the section that contains the CCF centroid of Parabigeminal nucleus according to the Allen image-to-atlas alignment (reference_to_image), with a 2 mm window around that point. Left: whole section, red box = window. Middle: ISH signal. Right: Allen's expression-mask view of the same window. open this image in the Allen viewer

Look it up yourself: Allen Mouse Brain ISH for Kcna3 Allen reference atlas: PBG (structure 874)ABC Atlas MERFISH viewer(in the ABC Atlas choose dataset MERFISH-C57BL6J-638850-CCF, colour cells by gene "Kcna3" or by parcellation_substructure "PBG")All genes confined to PBG + 3-D brain

Direct spatial evidence

PBG MERFISH region locator — Real single-cell MERFISH coordinates for the PBG (Parabigeminal nucleus) section -- our own ground-truth data, showing exactly where this region sits, independent of whether the Allen ISH section below is easy to read.

Regional expression figure

Predicted WMB × fine-CCF profile; not direct full-transcriptome spatial measurement.

Spatial profile

PBG

0.22

0.196

PVT

0.158

SAG

0.139

ILA2/3

0.135

0.134

0.128

PL2/3

0.126

ILA5

0.125

AIp6b

0.122

PMv

0.121

EPd

0.121

0.12

SPFm

0.119

VMH

0.118

LDT

0.118

ORBm5

0.113

PSTN

0.112

VISam4

0.111

TEa5

0.11

Evidence and specificity

Evidence status: PREDICTED_FINE
Direct sources: None; predicted localization only
Exclusive threshold: 12 positive regions out of 554
Spatial specificity: 0.276
Top-region fraction: 0.053
Filter status: PASS

Interpretation limits

Cell-type-to-region projection is imputed expression, not direct spatial measurement.
Adult reference atlases do not establish stability across age, sex, strain, state, or disease.
Transcript abundance does not guarantee protein abundance or genetic-tool performance.