Affinage

PASK

STE20/SPS1-related proline-alanine-rich protein kinase · UniProt Q9UEW8

Length
545 aa
Mass
59.5 kDa
Annotated
2026-06-10
29 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PASK (PASKIN) is an evolutionarily conserved PAS domain–containing serine/threonine kinase that couples nutrient and metabolic signals to gene-regulatory and transport programs, most prominently the entry of progenitor cells into differentiation (PMID:27661449, PMID:37052079). Its kinase domain adopts a catalytically active conformation and phosphorylates substrates without activation-loop phosphorylation, preferring basic residues at the P-3 and P-5 positions (PMID:20943661), with catalytic competence further stabilized by nutrient-responsive assembly of an intramolecular third PAS domain (PAS-C) that repositions PAS-A against the activation loop (PMID:40106358). In the resting state, an intramolecular PAS-A/PIM interaction masks a nuclear localization sequence within PAS-A, retaining PASK in the cytosol (PMID:38182104); metabolic inputs—including glutamine-metabolism-driven CBP/EP300-dependent acetylation and mTORC1-mediated phosphorylation—disrupt this restraint and license nuclear import (PMID:31072927, PMID:37052079). Nuclear PASK drives differentiation by phosphorylating WDR5 to convert H3K4me1 to H3K4me3 at the myogenin promoter (PMID:27661449), associating with the MLL2 H3K4 methyltransferase complex and directly phosphorylating histone H3 (PMID:31529049), and catalytically displacing WDR5 from the APC/C to extinguish post-mitotic self-renewal (Pax7 loss) (PMID:37052079). Independently of this nuclear role, PASK phosphorylates and activates the Na-K-Cl cotransporter NKCC1 (PMID:12740379) and phosphorylates eEF1A1 at Thr432 to stimulate translation (PMID:17595531). Genetically, a gain-of-function PASK mutation (p.G1117E) identified in a young-onset diabetes family elevates kinase activity and dysregulates insulin secretion from mouse islets (PMID:22065581).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 2000 High

    Established that PASK has a conserved, essential physiological function by showing the mammalian gene can substitute for its Drosophila ortholog in vivo.

    Evidence Genetic null mutant analysis with transgenic rescue using rat PASK cDNA in fly ensheathing glia

    PMID:11163267

    Open questions at the time
    • Does not define the molecular substrate or mechanism underlying glial ensheathment
    • Conservation of mechanism in mammals not directly tested
  2. 2003 High

    Identified the first direct PASK substrate and a transport function, showing PASK binds and phosphorylates NKCC1 to activate ion cotransport.

    Evidence Dominant-negative overexpression, 32Pi phosphorylation assay, and reciprocal co-immunoprecipitation in HEK cells

    PMID:12740379

    Open questions at the time
    • Upstream signals controlling PASK-NKCC1 engagement not defined
    • Physiological context of NKCC1 regulation by PASK unclear
  3. 2003 High

    Defined PASK expression and tested a candidate reproductive role, finding germ-cell upregulation but no requirement for fertility, narrowing its essential functions.

    Evidence Targeted knockout mouse with lacZ reporter and promoter analysis

    PMID:12972598

    Open questions at the time
    • Functional redundancy masking phenotype not excluded
    • Significance of shared promoter with Ppp1r7/Sds22 not mechanistically resolved
  4. 2007 High

    Resolved a controversy over a beta-cell glucose-sensing role by showing PASK is not expressed in islet beta-cells and is dispensable for glucose homeostasis in mice.

    Evidence lacZ reporter knock-in mouse, X-gal staining, insulin assays, and glucose tolerance testing

    PMID:17472472

    Open questions at the time
    • Does not rule out PASK roles in other metabolic tissues
    • Species or context differences from gain-of-function human data unresolved
  5. 2007 High

    Linked PASK to translational control by identifying eEF1A1 as a direct substrate phosphorylated at Thr432 and showing PASK stimulates translation.

    Evidence Yeast/mammalian two-hybrid, GST pulldown, in vitro kinase assay, mass spectrometry, mutagenesis, and in vitro translation assay

    PMID:17595531

    Open questions at the time
    • In vivo significance of Thr432 phosphorylation not established
    • Connection between translational and nuclear functions unclear
  6. 2010 High

    Explained how PASK is constitutively active, showing the kinase domain adopts an active fold without activation-loop phosphorylation and defining its substrate consensus.

    Evidence X-ray crystallography, in vitro kinase assays, mutagenesis, and combinatorial peptide library screening

    PMID:20943661

    Open questions at the time
    • How full-length regulatory domains gate this intrinsic activity not addressed
    • Cellular activation triggers not defined by structure alone
  7. 2011 Medium

    Proposed multiligand regulation of PASK by showing phosphatidylinositol species and additional substrates (ribosomal protein S6) modulate kinase activity.

    Evidence In vitro kinase, autophosphorylation, and phospholipid binding assays

    PMID:21418524

    Open questions at the time
    • Lipid regulation not demonstrated in cells
    • Physiological relevance of S6 phosphorylation unconfirmed
  8. 2011 High

    Connected PASK kinase activity to human disease by characterizing a young-onset diabetes gain-of-function mutation that alters insulin secretion.

    Evidence Affinity-purified kinase activity assays, adenoviral expression in mouse islets, and insulin secretion assays

    PMID:22065581

    Open questions at the time
    • Tension with reporter data showing no PASK in beta-cells unresolved
    • Causal substrate mediating altered secretion not identified
  9. 2016 High

    Defined PASK's nuclear epigenetic function, showing it phosphorylates WDR5 to remodel H3K4 methylation and initiate differentiation gene transcription.

    Evidence Loss/gain-of-function, ChIP, in vitro WDR5 kinase assay, reporter and differentiation assays across multiple progenitor types

    PMID:27661449

    Open questions at the time
    • Upstream signals triggering nuclear PASK activity not yet defined
    • Direct WDR5 phosphosite consequences on complex assembly incomplete
  10. 2019 High

    Placed PASK downstream of mTORC1, establishing an mTORC1–PASK–Wdr5 axis required for exit from self-renewal during early myogenesis.

    Evidence Genetic epistasis with rapamycin and S6K knockout, phosphorylation and myogenin reporter assays in muscle stem cells

    PMID:31072927

    Open questions at the time
    • Direct mTORC1 phosphosite on PASK not mapped
    • How phosphorylation activates nuclear PASK function not detailed
  11. 2019 Medium

    Extended PASK's chromatin activity, showing direct histone H3 phosphorylation and association with the MLL2 H3K4 methyltransferase complex.

    Evidence Co-immunoprecipitation, in vitro histone kinase assay, and CRISPR/Cas9 functional studies in satellite cells

    PMID:31529049

    Open questions at the time
    • In vivo histone phosphorylation sites not validated genetically
    • Reciprocal validation of MLL2 association limited to single lab
  12. 2023 High

    Identified the metabolic trigger and a non-transcriptional nuclear mechanism, showing glutamine-driven acetylation releases PASK to displace WDR5 from APC/C and terminate self-renewal.

    Evidence Live-cell imaging, fractionation, glutamine-metabolism perturbation, in vitro kinase competition, and mouse muscle regeneration assays

    PMID:37052079

    Open questions at the time
    • Acetylation sites on PASK not mapped
    • Mechanism by which displacement alters APC/C substrate selection incomplete
  13. 2024 Medium

    Resolved how cytoplasmic retention is controlled, identifying a PAS-A NLS masked by an intramolecular PIM interaction that metabolic signals disrupt to permit nuclear import.

    Evidence NLS mutagenesis, intramolecular interaction mapping, nuclear import assays, and ligand binding assays

    PMID:38182104

    Open questions at the time
    • Endogenous metabolic ligand disrupting PAS-PIM not identified
    • Quantitative kinetics of import switch not established
  14. 2025 Medium

    Revealed the structural basis of nutrient-responsive activation, defining a third PAS domain (PAS-C) whose assembly repositions PAS-A to stabilize the activation loop.

    Evidence Evolutionary domain mapping, deep-learning structural modeling, cross-linking assays, and biochemical kinase activity assays

    PMID:40106358

    Open questions at the time
    • Experimental high-resolution structure of PAS-C lacking
    • Direct nutrient ligand sensed by PAS-C not identified

Open questions

Synthesis pass · forward-looking unresolved questions
  • The identity of the physiological metabolic ligands sensed by PASK's PAS domains and how these unify its transport, translational, and chromatin functions remain unresolved.
  • No direct endogenous PAS-domain ligand identified
  • Integration of cytoplasmic (NKCC1, eEF1A1) and nuclear (WDR5, histone, APC/C) functions not mechanistically reconciled

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 6 GO:0016740 transferase activity 4 GO:0140110 transcription regulator activity 2 GO:0008092 cytoskeletal protein binding 1 GO:0008289 lipid binding 1
Localization
GO:0005634 nucleus 4 GO:0005829 cytosol 3 GO:0005856 cytoskeleton 1
Pathway
R-HSA-1266738 Developmental Biology 3 R-HSA-162582 Signal Transduction 2 R-HSA-4839726 Chromatin organization 2 R-HSA-382551 Transport of small molecules 1
Partners
APC/CEEF1A1MLL2NKCC1WDR5

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2003 PASK (SPAK) directly binds to and phosphorylates NKCC1 (Na-K-Cl cotransporter), activating it; a kinase-inactive dominant-negative PASK mutant reduces NKCC1 activity by 60-80% and blocks phosphorylation of two N-terminal regulatory threonines on NKCC1; co-immunoprecipitation confirmed constitutive PASK-NKCC1 association in HEK cells. Dominant-negative overexpression, 32Pi phosphorylation assay, co-immunoprecipitation, calyculin A rescue experiment The Journal of biological chemistry High 12740379
2000 Fray, the Drosophila ortholog of mammalian PASK, is required in peripheral glia for axonal ensheathment; rat PASK cDNA rescues fray null mutant nerve morphology defects, demonstrating functional conservation. Genetic null mutant analysis, transgenic rescue with rat PASK cDNA expressed in ensheathing glia Neuron High 11163267
2003 Mouse PASKIN is strongly upregulated in postmeiotic germ cells during spermatogenesis; the Paskin knockout mouse is viable and fertile with no spermatogenesis defect. The Paskin gene shares its promoter with Ppp1r7 (Sds22, a regulatory subunit of protein phosphatase 1), and Sds22 co-localizes with PASKIN-expressing cell types in vivo. Targeted gene knockout (homologous recombination), lacZ reporter knock-in for expression mapping, promoter analysis Molecular and cellular biology High 12972598
2010 Crystal structure of the human PASK kinase domain reveals it adopts an active conformation and has catalytic activity in vitro and in vivo without activation loop phosphorylation; site-directed mutagenesis identified key structural features enabling this; combinatorial peptide library screening determined PASK prefers basic residues at P-3 and P-5 positions in substrates. X-ray crystallography, in vitro kinase assay, site-directed mutagenesis, combinatorial peptide library screening The Journal of biological chemistry High 20943661
2007 PASKIN localizes to nuclei of human testis germ cells and the midpiece of sperm tails; it also shows a speckle-like nuclear pattern in HeLa cells in addition to cytoplasmic localization. PASKIN interacts with eEF1A1 (eukaryotic translation elongation factor 1A1) via its PAS-A and kinase domains (mapped by mammalian two-hybrid and GST pulldown); PASKIN phosphorylates eEF1A1 primarily at Thr432 (confirmed by mass spectrometry and mutagenesis); wild-type but not kinase-inactive PASKIN increases in vitro translation of a reporter cRNA. Immunofluorescence/localization, yeast two-hybrid screening, mammalian two-hybrid, GST pulldown, in vitro kinase assay, mass spectrometry, site-directed mutagenesis, in vitro translation assay Cellular physiology and biochemistry High 17595531
2011 Ribosomal protein S6 is identified as a novel PASKIN kinase substrate in addition to eEF1A1; phospholipids, particularly monophosphorylated phosphatidylinositols, bind PASKIN and stimulate autophosphorylation via the kinase domain (not the PAS domain); di- and tri-phosphorylated phosphatidylinositols inhibit both autophosphorylation and target phosphorylation, suggesting multiligand regulation of PASKIN activity. In vitro kinase assays, phospholipid binding assays, autophosphorylation assays The FEBS journal Medium 21418524
2011 A gain-of-function mutation in PASK (p.G1117E), identified in a young-onset diabetes family, increases autophosphorylation ~25% and kinase activity ~2-fold toward exogenous substrates; mouse islets infected with adenovirus expressing p.G1117E PASK show a 4-fold increase in basal (low glucose) insulin release and attenuated glucose-stimulated insulin secretion. The p.L1051V mutation did not affect kinase activity. Affinity-purified kinase activity assay (autophosphorylation at Thr307, peptide substrate), adenoviral expression in mouse islets, insulin secretion assay The Journal of biological chemistry High 22065581
2007 PASKIN is not expressed in pancreatic islet beta-cells (no X-gal staining in beta-cells of Paskin-lacZ reporter mice at any glucose concentration); glucose-stimulated insulin production and blood glucose regulation are independent of PASKIN in mice. lacZ reporter knock-in mouse, X-gal staining, adenoviral lacZ control, insulin mRNA and release assays, glucose tolerance test Diabetes High 17472472
2016 PASK phosphorylates Wdr5 (a member of H3K4 methyltransferase complexes) during myoblast differentiation, promoting conversion of H3K4me1 to H3K4me3 marks on the myogenin (Myog) promoter, enhancing MyoD accessibility and transcriptional activation of myogenin to initiate muscle differentiation; PASK also promotes differentiation of embryonic stem cells and adipogenic progenitor cells. Loss-of-function and gain-of-function experiments, chromatin immunoprecipitation (ChIP), in vitro kinase assay for Wdr5 phosphorylation, reporter assays, differentiation assays eLife High 27661449
2019 mTORC1 phosphorylates PASK in muscle stem cells during differentiation; this mTORC1-dependent PASK phosphorylation is required for myogenin transcription, exit from self-renewal, and induction of the myogenesis program (early stage), acting via PASK-Wdr5 signaling, distinct from mTORC1-S6K signaling required for later myoblast fusion. Genetic epistasis (mTOR inhibitor rapamycin, S6K knockout), phosphorylation assays, muscle stem cell differentiation assays, myogenin reporter assays Proceedings of the National Academy of Sciences of the United States of America High 31072927
2019 Nuclear PASK associates with the mammalian MLL2 H3K4 methyltransferase complex and enhances H3K4 di- and tri-methylation; PASK directly phosphorylates histone H3 at T3, T6, S10, and T11. Loss- or gain-of-function of PASK using CRISPR/Cas9 affects muscle satellite cell differentiation through regulation of these histone modifications. Co-immunoprecipitation, in vitro histone kinase assay, CRISPR/Cas9 loss/gain-of-function, muscle satellite cell differentiation assay Nucleic acids research Medium 31529049
2023 Mitochondrial glutamine metabolism drives CBP/EP300-dependent acetylation of PASK, releasing it from cytoplasmic granules and enabling nuclear translocation; in the nucleus, PASK catalytically displaces WDR5 from the anaphase-promoting complex/cyclosome (APC/C), resulting in loss of post-mitotic Pax7 expression and exit from stem cell self-renewal to establish differentiation competence. Live-cell imaging, subcellular fractionation, genetic/pharmacological inhibition of glutamine metabolism, in vitro kinase competition assay, muscle regeneration assay in mice eLife High 37052079
2024 The PAS-A domain of PASK contains a monopartite nuclear localization sequence (NLS) that is inhibited by intramolecular association with a short linear motif (PAS Interacting Motif, PIM) located upstream of the kinase domain; this PAS-PIM interaction retains PASK in the cytosol in the absence of signaling; metabolic inputs disrupt this interaction to induce PASK nuclear import, with PIM recruitment and artificial ligand binding occurring at neighboring locations on PAS-A. Mutagenesis of NLS, intramolecular interaction mapping (biochemical assays), nuclear import assays, ligand binding assays Journal of molecular biology Medium 38182104
2025 PASK contains a previously unrecognized third PAS domain (PAS-C) formed through intramolecular interactions between an N-terminal PAS fold and a C-terminal PAC motif separated by an unstructured linker; PAS-C assembly is nutrient-responsive and drives quaternary structure reorganization that positions PAS-A near the kinase activation loop, stabilizing it for catalytic activation. Evolutionary sequence/domain mapping, deep learning structural modeling, residue-level cross-linking assays, biochemical kinase activity assays Proceedings of the National Academy of Sciences of the United States of America Medium 40106358
2008 The kinase domain of PASK (SPAK) directly binds purified tubulin and microtubules in vitro; truncated PASK lacking the N-terminal non-catalytic domain promotes microtubule assembly at subcritical tubulin concentrations; FLAG-PASK expressed in COS-7 cells translocates to the cytoskeleton upon hypertonic NaCl stimulation and stabilizes microtubules against nocodazole-induced depolymerization. Tubulin binding assay, microtubule sedimentation (ultracentrifugation), in vitro microtubule assembly assay, FLAG-PASK overexpression with immunofluorescence and nocodazole treatment Archives of biochemistry and biophysics Medium 18675246

Source papers

Stage 0 corpus · 29 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 PASK (proline-alanine-rich STE20-related kinase), a regulatory kinase of the Na-K-Cl cotransporter (NKCC1). The Journal of biological chemistry 220 12740379
2000 Fray, a Drosophila serine/threonine kinase homologous to mammalian PASK, is required for axonal ensheathment. Neuron 109 11163267
2021 Adipose-Specific PPARα Knockout Mice Have Increased Lipogenesis by PASK-SREBP1 Signaling and a Polarity Shift to Inflammatory Macrophages in White Adipose Tissue. Cells 60 35011564
2003 Targeted disruption of the mouse PAS domain serine/threonine kinase PASKIN. Molecular and cellular biology 36 12972598
2009 FARP2, HDLBP and PASK are downregulated in a patient with autism and 2q37.3 deletion syndrome. American journal of medical genetics. Part A 34 19365831
2010 Structural bases of PAS domain-regulated kinase (PASK) activation in the absence of activation loop phosphorylation. The Journal of biological chemistry 27 20943661
2019 Activation of PASK by mTORC1 is required for the onset of the terminal differentiation program. Proceedings of the National Academy of Sciences of the United States of America 26 31072927
2001 Mammalian PASKIN, a PAS-serine/threonine kinase related to bacterial oxygen sensors. Biochemical and biophysical research communications 26 11688972
2009 The PAS-domain kinase PASKIN: a new sensor in energy homeostasis. Cellular and molecular life sciences : CMLS 25 19189049
2007 Male germ cell expression of the PAS domain kinase PASKIN and its novel target eukaryotic translation elongation factor eEF1A1. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 24 17595531
2015 Per-Arnt-Sim Kinase (PASK): An Emerging Regulator of Mammalian Glucose and Lipid Metabolism. Nutrients 21 26371032
2011 Human mutation within Per-Arnt-Sim (PAS) domain-containing protein kinase (PASK) causes basal insulin hypersecretion. The Journal of biological chemistry 19 22065581
2016 Pask integrates hormonal signaling with histone modification via Wdr5 phosphorylation to drive myogenesis. eLife 17 27661449
2008 Ventilatory responses to acute and chronic hypoxia are altered in female but not male Paskin-deficient mice. American journal of physiology. Regulatory, integrative and comparative physiology 17 18509100
2007 Glucose-stimulated insulin production in mice deficient for the PAS kinase PASKIN. Diabetes 17 17192472
2000 Isolation and expression of PASK, a serine/threonine kinase, during rat embryonic development, with special emphasis on the pancreas. The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society 14 10990492
2021 Preventing Oxidative Stress in the Liver: An Opportunity for GLP-1 and/or PASK. Antioxidants (Basel, Switzerland) 12 34943132
2021 Storage and Utilization of Glycogen by Mouse Liver during Adaptation to Nutritional Changes Are GLP-1 and PASK Dependent. Nutrients 11 34444712
2019 The metabolic sensor PASK is a histone 3 kinase that also regulates H3K4 methylation by associating with H3K4 MLL2 methyltransferase complex. Nucleic acids research 11 31529049
2011 Substrate preference and phosphatidylinositol monophosphate inhibition of the catalytic domain of the Per-Arnt-Sim domain kinase PASKIN. The FEBS journal 11 21418524
2023 PASK links cellular energy metabolism with a mitotic self-renewal network to establish differentiation competence. eLife 10 37052079
2011 Per-arnt-sim (PAS) domain kinase (PASK) as a regulator of glucagon secretion. Diabetologia 10 21327866
2018 Per-Arnt-Sim Kinase (PASK) Deficiency Increases Cellular Respiration on a Standard Diet and Decreases Liver Triglyceride Accumulation on a Western High-Fat High-Sugar Diet. Nutrients 7 30558306
2024 Signal-regulated Unmasking of Nuclear Localization Motif in the PAS Domain Regulates the Nuclear Translocation of PASK. Journal of molecular biology 3 38182104
2008 PASK (proline-alanine-rich Ste20-related kinase) binds to tubulin and microtubules and is involved in microtubule stabilization. Archives of biochemistry and biophysics 3 18675246
2025 Structural assembly of the PAS domain drives the catalytic activation of metazoan PASK. Proceedings of the National Academy of Sciences of the United States of America 2 40106358
2023 Jasminoidin reduces ischemic stroke injury by regulating microglia polarization via PASK-EEF1A1 axis. Chemical biology & drug design 2 37743322
2024 Nutrient Signaling-Dependent Quaternary Structure Remodeling Drives the Catalytic Activation of metazoan PASK. bioRxiv : the preprint server for biology 0 38979257
2023 Signal-regulated unmasking of the nuclear localization motif in the PAS domain regulates the nuclear translocation of PASK. bioRxiv : the preprint server for biology 0 37732199

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