Affinage

PIRT

Phosphoinositide-interacting protein · UniProt P0C851

Length
137 aa
Mass
15.3 kDa
Annotated
2026-04-28
20 papers in source corpus 10 papers cited in narrative 10 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PIRT is a two-transmembrane domain membrane protein expressed in peripheral sensory neurons that functions as a broad modulatory subunit of ion channels and purinergic receptors to regulate nociception, thermosensation, and itch. Its C-terminus directly binds both TRPV1 and PIP2 via a cluster of basic residues, and PIP2-dependent enhancement of TRPV1 activity requires PIRT, as demonstrated by impaired noxious heat and capsaicin responses in Pirt-null mice (PMID:18455988). PIRT also modulates TRPM8 by binding the S1-S4 transmembrane domain and competing with TRPM8 for PIP2, with species-specific effects—enhancing mouse TRPM8 but attenuating human TRPM8—mapped to the pore domain (PMID:29724821, PMID:31575973). Through its N-terminal 14 residues, PIRT inhibits P2X3 receptor activity to suppress bladder overactivity, and it additionally binds calmodulin and cholesterol derivatives, indicating ligand-binding functions beyond TRP channel regulation (PMID:26151598, PMID:32245175).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2008 High

    The discovery that PIRT directly binds TRPV1 and PIP2 via its C-terminus and is required for normal noxious heat and capsaicin sensitivity established PIRT as a regulatory subunit of TRPV1 and a critical component of nociceptive signaling.

    Evidence Co-immunoprecipitation, mutagenesis of C-terminal basic residues, whole-cell electrophysiology, and Pirt knockout mice with behavioral phenotyping

    PMID:18455988

    Open questions at the time
    • Stoichiometry of the PIRT–TRPV1 complex not determined
    • Whether PIRT modulates TRPV1 trafficking versus gating not resolved
    • Structural basis of the PIRT C-terminus–TRPV1 interaction unknown
  2. 2011 Medium

    Demonstrating that Pirt-null mice have defective itch responses to both histamine-dependent and histamine-independent pruritogens—including TRPV1-independent itch—revealed that PIRT's sensory modulatory role extends beyond TRPV1 to additional itch pathways.

    Evidence Pirt knockout mouse behavioral assays with multiple pruritogens and DRG neuron calcium imaging

    PMID:21655234

    Open questions at the time
    • The specific channel or receptor targets mediating PIRT-dependent itch signaling beyond TRPV1 were not identified
    • Mechanism by which PIRT modulates TRPV1-independent itch unknown
  3. 2013 High

    Identifying PIRT as a positive regulator of TRPM8 that is required for normal cold/cool behavioral responses expanded PIRT's role from nociception to thermosensation.

    Evidence Pirt knockout mouse behavioral assays (cold plate, acetone) and heterologous co-expression electrophysiology with TRPM8

    PMID:23863968

    Open questions at the time
    • Binding interface between PIRT and TRPM8 not yet mapped
    • Whether PIP2 mediates PIRT's effect on TRPM8 not tested
  4. 2015 High

    Mapping the N-terminal 14 residues of PIRT as sufficient for P2X3 receptor inhibition and showing that PIRT deficiency causes bladder overactivity demonstrated a distinct, non-TRP channel regulatory function with therapeutic relevance.

    Evidence Co-immunoprecipitation, domain-mapping electrophysiology, Pirt knockout bladder function assays, TAT-peptide rescue in vivo

    PMID:26151598

    Open questions at the time
    • Structural basis of PIRT N-terminus–P2X3 interaction unknown
    • Whether PIRT modulates other P2X family members not tested
  5. 2015 Medium

    Single-channel recordings showing PIRT increases TRPM8 single-channel conductance, synergistically with PIP2, provided a biophysical mechanism for PIRT's enhancement of TRPM8.

    Evidence Cell-attached single-channel recordings in CHO cells co-expressing TRPM8 and PIRT, with intracellular PIP2 application

    PMID:26657057

    Open questions at the time
    • Whether PIRT changes TRPM8 open probability versus conductance not fully dissected
    • Mechanism by which PIRT alters conductance at the structural level unknown
  6. 2018 High

    Discovering that human PIRT attenuates human TRPM8 (opposite to mouse) and that the species difference maps to the TRPM8 pore domain revealed a species-specific regulatory mechanism; NMR and pulldown demonstrated ~1:1 stoichiometric binding of PIRT to the TRPM8 S1-S4 domain.

    Evidence Comparative electrophysiology with chimeric TRPM8 channels, NMR spectroscopy and pulldown with purified proteins, quantitative Western blot for surface expression

    PMID:29724821

    Open questions at the time
    • Atomic-resolution structure of PIRT–TRPM8 complex not available
    • Physiological consequence of species-specific modulation in vivo not tested
  7. 2018 Medium

    Epistasis experiments in Pirt/TRPV1 double-knockout mice showed additive pain attenuation in a neuropathic pain model, formally placing PIRT within but not exclusively through the TRPV1 pathway in chronic pain.

    Evidence Chronic constriction injury model in Pirt knockout and Pirt/TRPV1 double-knockdown mice, behavioral and calcium imaging assays

    PMID:29808083

    Open questions at the time
    • Additional PIRT targets contributing to neuropathic pain not identified
    • Mechanism of PIRT upregulation or sensitization after nerve injury unknown
  8. 2019 High

    NMR backbone assignments of full-length human PIRT and competitive binding assays established that PIRT and TRPM8 compete for PIP2, providing a mechanistic model in which PIRT modulates TRPM8 by controlling local PIP2 availability.

    Evidence Solution NMR spectroscopy (backbone assignment), microscale thermophoresis binding assays, computational PIP2 docking

    PMID:31575973

    Open questions at the time
    • Full three-dimensional structure of PIRT not resolved
    • In vivo evidence for PIP2 competition model lacking
  9. 2020 Medium

    Identification of calmodulin binding at the PIRT C-terminal helix and cholesterol/cholecalciferol binding at a CRAC motif in the first transmembrane helix broadened PIRT's known ligand repertoire beyond PIP2 and channel partners.

    Evidence Microscale thermophoresis, pulldown, NMR-detected binding, Rosetta modeling

    PMID:32245175

    Open questions at the time
    • Functional consequence of calmodulin and cholesterol binding on channel modulation not tested
    • Findings from a single lab without independent replication
    • Whether oxytocin binding is physiologically relevant is untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • A high-resolution structure of PIRT alone or in complex with its channel partners is lacking, the full set of ion channels regulated by PIRT remains undefined, and the in vivo relevance of PIRT's calmodulin and cholesterol binding is unknown.
  • No high-resolution structure of PIRT or PIRT–channel complex
  • Full repertoire of PIRT-regulated channels not mapped
  • In vivo relevance of calmodulin and cholesterol binding untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 4 GO:0008289 lipid binding 3
Localization
GO:0005886 plasma membrane 3
Pathway
R-HSA-112316 Neuronal System 4 R-HSA-162582 Signal Transduction 4
Partners
CALMODULINP2X3PIP2TRPM8TRPV1

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2008 PIRT functions as a regulatory subunit of TRPV1: the C-terminus of PIRT directly binds TRPV1 and phosphoinositides including PIP2 (via a cluster of basic residues), and PIP2-dependent enhancement of TRPV1 activity requires PIRT. Pirt null mice show impaired noxious heat and capsaicin responsiveness, and heterologous expression of PIRT strongly enhances TRPV1-mediated currents. Co-immunoprecipitation/pulldown (PIRT C-terminus binds TRPV1 and PIP2), whole-cell electrophysiology in heterologous cells and DRG neurons, Pirt knockout mice with behavioral and electrophysiological phenotyping, mutagenesis of basic residues in C-terminus Cell High 18455988
2013 PIRT is an endogenous positive regulator of TRPM8: Pirt-/- mice show decreased behavioral responses to cold/cool temperatures, and PIRT increases TRPM8 sensitivity to menthol and cool temperature in heterologous expression systems. Pirt knockout mouse behavioral assays (cold plate, acetone evaporation), whole-cell electrophysiology in heterologous cells co-expressing PIRT and TRPM8 Nature communications High 23863968
2015 PIRT negatively regulates P2X3 receptor activity in bladder DRG neurons through a direct interaction mediated by the N-terminal 14 amino acid residues of PIRT; PIRT deficiency causes bladder overactivity, and a TAT-conjugated Pirt(N14) peptide is sufficient to inhibit P2X3 activation and alleviate bladder overactivity. Co-localization (immunofluorescence), co-immunoprecipitation (PIRT with P2X3), whole-cell electrophysiology in DRG neurons and heterologous cells, Pirt-/- mouse bladder function assays, TAT-peptide rescue experiment Nature communications High 26151598
2015 PIRT and PIP2 synergistically enhance TRPM8 channel activity; the mechanism involves PIRT increasing the single-channel conductance of TRPM8 as shown by cell-attached single-channel recordings. Whole-cell patch-clamp electrophysiology with intracellular PIP2 application, cell-attached single-channel recordings in CHO cells transfected with TRPM8 ± PIRT Acta pharmacologica Sinica Medium 26657057
2011 PIRT is required for both histamine-dependent and -independent itch, including forms of itch that are TRPV1-independent, demonstrating that PIRT's function extends beyond TRPV1 modulation to multiple itch signaling pathways. Pirt-/- mouse behavioral assays with multiple pruritogens, DRG neuron calcium imaging PloS one Medium 21655234
2018 Human PIRT attenuates human TRPM8 conductance (opposite to mouse PIRT which enhances mouse TRPM8), and PIRT binds directly and specifically to the TRPM8 S1-S4 transmembrane domain with approximately 1:1 stoichiometry. This species-specific difference maps to the pore domain of TRPM8. Comparative electrophysiology (human vs mouse TRPM8 ± PIRT in heterologous cells), chimeric TRPM8 channels, quantitative Western blot for surface trafficking, NMR spectroscopy and pulldown assay (recombinant purified human TRPM8 S1-S4 domain and full-length human PIRT) The Journal of biological chemistry High 29724821
2019 PIRT, TRPM8, and PIP2 form a regulatory complex in which PIRT competes with TRPM8 for PIP2 binding; PIRT modulation of TRPM8 arises at least in part by regulating local concentrations of PIP2 accessible to TRPM8. NMR backbone assignments of full-length human PIRT were obtained, and competitive interactions between PIRT and TRPM8 S1-S4 domain for PIP2 were demonstrated. Solution NMR spectroscopy (backbone resonance assignment of full-length human PIRT, binding studies), microscale thermophoresis (MST) binding assays, computational PIP2 docking to TRPM8 model Scientific reports High 31575973
2020 PIRT binds calmodulin at its C-terminal α-helix, and also contains a cholesterol-recognition amino acid consensus (CRAC) domain in its first transmembrane helix through which it specifically binds cholesterol derivatives, cholecalciferol, and oxytocin, suggesting broader ligand-binding capacity beyond TRP channels and PIP2. Microscale thermophoresis (MST), pulldown assay, NMR-detected binding, Rosetta-based computational modeling Biomolecules Medium 32245175
2016 PIRT co-localizes with P2X2 receptors in neurons of the mouse enteric nervous system (myenteric and submucosal plexuses), and co-immunoprecipitation shows PIRT and P2X2 are in the same complex, suggesting PIRT may regulate P2X2 receptor function in the gut. Immunofluorescence co-localization, co-immunoprecipitation Purinergic signalling Low 27105971
2018 PIRT together with TRPV1 contributes to neuropathic pain (CCI model): Pirt-/- mice show reduced mechanical allodynia and thermal hyperalgesia, and loss of both Pirt and TRPV1 produces greater pain attenuation than loss of either alone, placing PIRT in the TRPV1 signaling pathway for neuropathic pain. Pirt knockout and double knockdown (Pirt/TRPV1) mouse CCI model, behavioral assays, DRG neuron calcium imaging, immunofluorescence Neural plasticity Medium 29808083

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 Pirt, a phosphoinositide-binding protein, functions as a regulatory subunit of TRPV1. Cell 178 18455988
2020 Mapping of Sensory Nerve Subsets within the Vagal Ganglia and the Brainstem Using Reporter Mice for Pirt, TRPV1, 5-HT3, and Tac1 Expression. eNeuro 67 32060036
2013 Pirt functions as an endogenous regulator of TRPM8. Nature communications 46 23863968
2011 Pirt, a TRPV1 modulator, is required for histamine-dependent and -independent itch. PloS one 46 21655234
2022 scRNA-sequencing reveals subtype-specific transcriptomic perturbations in DRG neurons of Pirt mice in neuropathic pain condition. eLife 43 36264609
2018 Pirt Together with TRPV1 Is Involved in the Regulation of Neuropathic Pain. Neural plasticity 26 29808083
2015 Pirt reduces bladder overactivity by inhibiting purinergic receptor P2X3. Nature communications 20 26151598
2015 Pirt contributes to uterine contraction-induced pain in mice. Molecular pain 18 26376721
2018 Phosphoinositide-interacting regulator of TRP (PIRT) has opposing effects on human and mouse TRPM8 ion channels. The Journal of biological chemistry 12 29724821
2015 Phosphoinositide interacting regulator of TRP (Pirt) enhances TRPM8 channel activity in vitro via increasing channel conductance. Acta pharmacologica Sinica 10 26657057
2021 Ca2+ Signalling Induced by NGF Identifies a Subset of Capsaicin-Excitable Neurons Displaying Enhanced Chemo-Nociception in Dorsal Root Ganglion Explants from Adult pirt-GCaMP3 Mouse. International journal of molecular sciences 9 33806699
2023 piRT-IFC: Physics-informed real-time impedance flow cytometry for the characterization of cellular intrinsic electrical properties. Microsystems & nanoengineering 8 37303829
2021 [Involvement of Pirt /TRPV1 signaling in acupuncture-induced reduction of visceral hypersensitivity in diarrhea-predominant irritable bowel syndrome rats]. Zhen ci yan jiu = Acupuncture research 8 33931991
2019 Competitive Interactions between PIRT, the Cold Sensing Ion Channel TRPM8, and PIP2 Suggest a Mechanism for Regulation. Scientific reports 8 31575973
2016 Co-localization of Pirt protein and P2X2 receptors in the mouse enteric nervous system. Purinergic signalling 8 27105971
2021 Population Coding of Capsaicin Concentration by Sensory Neurons Revealed Using Ca2+ Imaging of Dorsal Root Ganglia Explants from Adult pirt-GCaMP3 Mouse. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 5 34242501
2020 PIRT the TRP Channel Regulating Protein Binds Calmodulin and Cholesterol-Like Ligands. Biomolecules 5 32245175
2019 Pirt deficiency has subtle female-specific effects on energy and glucose metabolism in mice. Molecular metabolism 4 30902502
2025 PIRT-Seq: a high-resolution whole-genome assay to identify protein-coding genes. Nucleic acids research 0 40808296
2025 In vivo Pirt-Marina voltage sensor imaging detects primary sensory neuron-specific voltage dynamics and neuronal plasticity changes. Proceedings of the National Academy of Sciences of the United States of America 0 40938705