Affinage

STK16

Serine/threonine-protein kinase 16 · UniProt O75716

Length
305 aa
Mass
34.7 kDa
Annotated
2026-06-10
10 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

STK16 is an intrinsically active serine/threonine protein kinase that links Golgi-associated actin dynamics to cell cycle progression and to control of oncogenic signaling (PMID:9712705, PMID:28294156). It is constitutively localized to the Golgi apparatus throughout the cell cycle, where it directly binds actin and regulates actin polymer organization in a concentration- and kinase-activity-dependent manner; loss of STK16 by knockdown or kinase inhibition disrupts actin polymers, fragments the Golgi, delays mitotic entry, and produces prometaphase and cytokinesis arrest with accumulation of binucleated cells (PMID:27082499, PMID:28294156). Golgi and membrane targeting depend on autophosphorylation within the activation segment, with Tyr198 being the essential site whose mutation reduces kinase activity, abolishes Golgi/membrane localization, and impairs cell cycle progression (PMID:31574902). Upon Golgi disorganization or overexpression, STK16 translocates to the nucleus independently of its catalytic activity (PMID:16310770). Its kinase activity is enhanced by physical interaction with N-acetylglucosamine kinase (GlcNAcK), which binds STK16 but is not itself a substrate (PMID:11741987). STK16 also drives proliferative signaling: it directly phosphorylates c-MYC at Ser452 to protect c-MYC from ubiquitin-proteasome degradation, supporting colorectal cancer growth (PMID:38622518), and its overexpression enhances VEGF production and secretion and increases tumor vascularity (PMID:16310770). Highly selective ATP-competitive inhibition phenocopies genetic loss, establishing that the kinase activity is required for these functions (PMID:27082499).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 1998 High

    Establishing that STK16/PKL12 is a bona fide catalytically active kinase was the founding question, settled by showing it phosphorylates substrate and autophosphorylates in isolation.

    Evidence In vitro kinase assay with bacterially purified recombinant protein, enolase substrate and autophosphorylation

    PMID:9712705

    Open questions at the time
    • No physiological substrate identified
    • No cellular localization or pathway context established
  2. 2001 High

    Identifying a binding partner that modulates activity addressed how STK16 catalysis is regulated, showing GlcNAcK binds and allosterically enhances kinase activity without being a substrate.

    Evidence Yeast two-hybrid screen, in vitro pulldown, in vivo co-localization in vesicular structures, in vitro kinase assay

    PMID:11741987

    Open questions at the time
    • Mechanism by which GlcNAcK enhances activity not resolved
    • Physiological relevance of the interaction not tested in loss-of-function context
  3. 2005 High

    Defining where STK16 acts addressed its compartmental role, establishing constitutive Golgi localization with kinase-independent nuclear translocation upon Golgi disruption, and linking it to VEGF secretion.

    Evidence Immunofluorescence, subcellular fractionation, kinase-dead E202A mutant, retroviral overexpression, in vivo xenograft

    PMID:16310770

    Open questions at the time
    • Functional consequence of nuclear pool unknown
    • Mechanism linking STK16 to VEGF secretion not defined
    • Golgi-targeting determinants not identified
  4. 2016 High

    A selective ATP-competitive inhibitor (STK16-IN-1) addressed whether catalytic activity itself drives the cell division phenotype, showing pharmacological inhibition phenocopies RNAi knockdown.

    Evidence Biochemical kinase inhibition, KinomeScan selectivity profiling, RNAi knockdown, binucleation/cell number assays in MCF-7

    PMID:27082499

    Open questions at the time
    • Relevant phosphorylation substrate for cell division not identified
    • Mechanism producing binucleation not resolved
  5. 2017 High

    Connecting STK16 to a direct molecular target addressed how it controls Golgi and mitosis, showing direct actin binding and kinase-activity-dependent regulation of actin dynamics underlying Golgi integrity and mitotic progression.

    Evidence In vitro actin-binding assay, siRNA knockdown, pharmacological inhibition, live-cell imaging, immunofluorescence

    PMID:28294156

    Open questions at the time
    • Whether actin is a phosphorylation substrate not established
    • Molecular link between actin regulation and cytokinesis arrest unresolved
  6. 2019 High

    Mapping the activation-segment autophosphorylation sites addressed how STK16 activity and localization are coupled, identifying Tyr198 as the essential site for both kinase activity and Golgi/membrane targeting.

    Evidence Site-directed mutagenesis of Thr185/Ser197/Tyr198, in vitro kinase assay, localization studies, cell cycle analysis

    PMID:31574902

    Open questions at the time
    • Upstream trigger of activation-segment autophosphorylation unknown
    • How Tyr198 phosphorylation drives membrane association mechanistically unresolved
  7. 2022 Medium

    Placing STK16 in a regulatory and survival circuit addressed its role in lung cancer, showing it acts via the AKT1 pathway and is transcriptionally controlled by ETS1 under miR-181a-5p regulation.

    Evidence siRNA knockdown, proliferation/apoptosis assays, luciferase reporter, ChIP, Western blot, mouse xenograft

    PMID:35092121

    Open questions at the time
    • Direct STK16 substrate in the AKT1 axis not identified
    • Whether STK16 acts upstream or in parallel to AKT1 not resolved
  8. 2024 Medium

    Identifying a direct phosphosubstrate addressed how STK16 promotes tumor growth, showing it phosphorylates c-MYC at Ser452 to block proteasomal degradation in colorectal cancer.

    Evidence Immunoprecipitation, phospho-specific immunoblot, in vitro kinase assay, S452 mutagenesis, ubiquitination assay, STK16 KO/inhibitor in vivo

    PMID:38622518

    Open questions at the time
    • Single-lab finding without full mechanistic reconstitution
    • How Golgi-localized STK16 accesses c-MYC not addressed
    • Generality beyond colorectal context untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How STK16's Golgi/actin role mechanistically integrates with its substrate phosphorylation events (c-MYC, AKT1 axis) and VEGF secretion into a single signaling logic remains unresolved.
  • No unified substrate map linking Golgi actin regulation to nuclear/oncogenic targets
  • Physiological upstream activators of STK16 unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 2 GO:0140096 catalytic activity, acting on a protein 2 GO:0008092 cytoskeletal protein binding 1 GO:0140657 ATP-dependent activity 1
Localization
GO:0005794 Golgi apparatus 3 GO:0005634 nucleus 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-1640170 Cell Cycle 2 R-HSA-1643685 Disease 2
Partners
ACTBMYCNAGK

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1998 PKL12 (STK16) encodes a serine/threonine protein kinase with intrinsic kinase activity capable of phosphorylating enolase and promoting autophosphorylation, as demonstrated using E. coli-purified protein in in vitro kinase assays. In vitro kinase assay with bacterially purified protein; substrate phosphorylation and autophosphorylation Biochemical and biophysical research communications High 9712705
2001 PKL12/STK16 physically interacts with N-acetylglucosamine kinase (GlcNAcK), confirmed by yeast two-hybrid and in vitro/in vivo binding assays. GlcNAcK colocalizes with PKL12 in vesicular structures near the cell membrane. GlcNAcK is not a substrate for PKL12 and does not modulate PKL12 autophosphorylation, but functional GlcNAcK greatly enhances PKL12 kinase activity on a defined substrate protein in vitro. Yeast two-hybrid screen, in vitro binding confirmation, in vivo co-localization, in vitro kinase assay The Journal of biological chemistry High 11741987
2005 Endogenous STK16/PKL12 localizes to the Golgi apparatus in NIH/3T3 and NRK cells; treatment with brefeldin A or nocodazole (Golgi disorganization agents) causes STK16 to translocate to the nuclear compartment. Constitutive overexpression also drives nuclear accumulation. A kinase-dead mutant (E202A) retains both Golgi association and nuclear translocation, indicating these localizations are independent of kinase activity. STK16 overexpression enhances VEGF production and secretion in vitro and increases tumor vascularity in vivo. Indirect immunofluorescence, subcellular fractionation, kinase-dead mutant (E202A), retroviral overexpression, in vivo xenograft model Experimental cell research High 16310770
2016 STK16-IN-1 was identified as a highly selective, ATP-competitive inhibitor of STK16 (IC50 = 0.295 µM, S score(1) = 0.0 across kinome). In MCF-7 cells, STK16-IN-1 treatment reduces cell number and causes accumulation of binucleated cells, phenocopying RNAi knockdown of STK16, establishing STK16 kinase activity as required for normal cell division. Biochemical kinase inhibition assay, KinomeScan profiling, RNAi knockdown, cell number/binucleation assay ACS chemical biology High 27082499
2017 STK16 localizes to the Golgi throughout the cell cycle and directly binds actin, regulating actin dynamics in a concentration- and kinase activity-dependent manner. STK16 knockdown or kinase inhibition disrupts actin polymers, causes Golgi fragmentation, delays mitotic entry, prolongs mitosis, and causes prometaphase and cytokinesis arrest. In vitro actin-binding assay, siRNA knockdown, pharmacological kinase inhibition, live-cell imaging, immunofluorescence Scientific reports High 28294156
2019 STK16 autophosphorylates at Thr185, Ser197, and Tyr198 within its activation segment. Mutation of Tyr198 alone significantly reduces kinase activity, abolishes Golgi and membrane localization, and impairs cell cycle progression, identifying Tyr198 as the essential autophosphorylation site for STK16 localization and function. Site-directed mutagenesis of autophosphorylation sites, in vitro kinase assay, subcellular localization studies (immunofluorescence/fractionation), cell cycle analysis International journal of molecular sciences High 31574902
2024 STK16 directly phosphorylates c-MYC at serine 452, which prevents c-MYC degradation via the ubiquitin-proteasome pathway. Colorectal cancer cell proliferation driven by STK16 depends on this phosphorylation event. STK16 knockout or pharmacological inhibition reduces c-MYC protein levels and curtails tumor growth in vivo. Immunoprecipitation, immunoblot (phospho-specific), in vitro kinase assay, site-directed mutagenesis (S452), ubiquitination assay, cell proliferation assays, in vivo animal model with STK16 KO/inhibitor Molecular medicine (Cambridge, Mass.) Medium 38622518
2022 STK16 knockdown inhibits LUAD cell proliferation and promotes apoptosis via the AKT1 pathway. STK16 is a transcriptional target of ETS1; miR-181a-5p (delivered via M1 macrophage exosomes) suppresses ETS1, thereby reducing STK16 expression and promoting apoptosis. siRNA knockdown, CCK-8 proliferation assay, apoptosis assay, luciferase reporter assay, ChIP assay, Western blotting, mouse xenograft model Cancer science Medium 35092121

Source papers

Stage 0 corpus · 10 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2022 Exosomes from M1-polarized macrophages promote apoptosis in lung adenocarcinoma via the miR-181a-5p/ETS1/STK16 axis. Cancer science 38 35092121
2001 Functional interaction between the Ser/Thr kinase PKL12 and N-acetylglucosamine kinase, a prominent enzyme implicated in the salvage pathway for GlcNAc recycling. The Journal of biological chemistry 26 11741987
2005 Nucleocytoplasmic shuttling of STK16 (PKL12), a Golgi-resident serine/threonine kinase involved in VEGF expression regulation. Experimental cell research 22 16310770
2017 STK16 regulates actin dynamics to control Golgi organization and cell cycle. Scientific reports 20 28294156
1998 Cloning, expression analysis, and functional characterization of PKL12, a member of a new subfamily of ser/thr kinases. Biochemical and biophysical research communications 20 9712705
2016 Discovery of a Highly Selective STK16 Kinase Inhibitor. ACS chemical biology 19 27082499
2019 Serine/Threonine Protein Kinase STK16. International journal of molecular sciences 17 30974739
2019 The STK16 inhibitor STK16-IN-1 inhibits non-adrenergic and non-neurogenic smooth muscle contractions in the human prostate and the human male detrusor. Naunyn-Schmiedeberg's archives of pharmacology 8 31867686
2019 Tyr198 is the Essential Autophosphorylation Site for STK16 Localization and Kinase Activity. International journal of molecular sciences 5 31574902
2024 STK16 promoted colorectal cancer progress in a c-MYC signaling-dependent manner. Molecular medicine (Cambridge, Mass.) 3 38622518

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