Mrgpra6

Mas-related G protein-coupled receptor member A6

Spatial tier: STRICT_EXCLUSIVE · Class: GPCR · Top region: PBG (Parabigeminal nucleus) · Positive regions: 6/554

44.4Discovery Score
34.6Targetability Score
CEvidence grade C
What this means: Mrgpra6: predicted fine-region profile is strict-exclusive, with 6 positive regions out of 554 (limit 12); direct spatial validation is required.

Function in PBG: evidence, prediction, innovation

Gene function
Mrgpra6 is a Mas-related GPCR in the rodent-expanded mouse chromosome 7 cluster, closest human relative MRGPRX3. Family members are Gq- or Gi-coupled receptors for peptides and cationic ligands mediating itch, nociception and pseudo-allergic mast cell degranulation. Mrgpra6 is basophil-restricted; knockout impairs early anti-helminth innate immunity, raising larval burden and mortality.
Region function
The parabigeminal nucleus (Ch8) is a cholinergic midbrain nucleus reciprocally linked to the superior colliculus, relaying visual information across hemispheres, sharpening SC surround inhibition and looming responses, and triggering freezing and escape.
Published in this region
inferred No region-specific literature found. Closest is Mrgpr-family expression mapping to small-diameter DRG and trigeminal sensory neurons and immune cells, explicitly not CNS, with Mrgpra6 only in blood and lung basophils (2026 basophil GPCR study).
Predicted function
Prediction: a genuine PBG signal would be the family's first CNS site; Gq coupling predicts depolarised cholinergic PBG neurons, more acetylcholine onto superficial SC and a lower escape threshold. Knockout or local antagonism should weaken looming-evoked defence without changing visual acuity. RNAscope with ChAT staining must first exclude contamination by sensory-like cells or blood basophils.
Innovation
★★★★☆ 4/5 No Mrgpr has a known central function and the PBG is tool-accessible, but expression needs validation.
Tools
Mrgpra6 knockout mice (2026 basophil study); Mrgpr cluster-deletion mice; no selective agonist or antagonist; PBG access via Chat-IRES-Cre (JAX 006410) with Cre-dependent AAV for optogenetics or DREADDs.
References

Direct evidence located at the region

No Allen ISH section could be located at this region's centroid for the recorded experiments.

Look it up yourself: Allen Mouse Brain ISH for Mrgpra6Allen reference atlas: PBG (structure 874)ABC Atlas MERFISH viewer(in the ABC Atlas choose dataset MERFISH-C57BL6J-638850-CCF, colour cells by gene "Mrgpra6" or by parcellation_substructure "PBG")All genes confined to PBG + 3-D brain

Direct spatial evidence

MERFISH REGION LOCATOR
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

Mrgpra6 regional expression profile

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

Spatial profile

PBG
0.164
PC5
0.125
IO
0.0945
B
0.0775
Pa5
0.0716
AD
0.0608
SPVI
0.056
EW
0.0548
RPA
0.0538
RL
0.0532
ICc
0.0528
LSc
0.0518
IPA
0.0515
PGRNd
0.0502
CS
0.0501
NLL
0.0499
CU
0.0496
CA2sp
0.0493
SAG
0.0492
TRN
0.0486

Evidence and specificity

Evidence status
PREDICTED_FINE
Direct sources
None; predicted localization only
Exclusive threshold
12 positive regions out of 554
Spatial specificity
0.316
Top-region fraction
0.097
Filter status
PASS

Interpretation limits