| Category | Key findings | Best supporting citations |
|---|---|---|
| Identity | Human **IP6K3** corresponds to **UniProt Q96PC2**; literature and kinase tables explicitly map **IP6K3 ↔ Q96PC2**. It is one of the mammalian inositol hexakisphosphate kinases within the broader inositol phosphate kinase pathway; no conflicting human target identity was found in the retrieved evidence. | 2026 FEBS Lett. table linking IP6K3 to Q96PC2: https://doi.org/10.1002/1873-3468.70280 (pqac-00000003); 2023 Biomolecules review on IP6Ks: https://doi.org/10.3390/biom13091317 (pqac-00000001) |
| Enzymatic reaction | IP6K3 is an **inositol hexakisphosphate kinase** that synthesizes inositol pyrophosphates. Current consensus is that IP6Ks convert **IP6 → 5-IP7 (5-InsP7)** and can further phosphorylate **1-IP7 → IP8**. | 2023 Biomolecules review: https://doi.org/10.3390/biom13091317 (pqac-00000001); 2016 Sci Rep: https://doi.org/10.1038/srep32072 (pqac-00000000) |
| Substrate specificity | Reported IP6K 5-kinase activity includes pyrophosphorylation of **InsP5 → 5-PP-InsP4**, **InsP6 → 5-PP-InsP5 (5-InsP7)**, and **1-PP-InsP5 → InsP8**; thus IP6K3 shares family substrate scope for highly phosphorylated inositols, with best-established physiological product **5-InsP7**. | 2016 Sci Rep: https://doi.org/10.1038/srep32072 (pqac-00000000); 2023 Biomolecules review: https://doi.org/10.3390/biom13091317 (pqac-00000001) |
| Localization & expression | Expression is enriched relative to IP6K1/2 in **skeletal muscle, cardiac muscle/heart, thyroid, and brain/cerebellum**; in brain, IP6K3 is highly expressed in **Purkinje cells** and also interneurons. In HEK293 cells, **GFP-IP6K3 localizes to both cytoplasm and nucleus**. In cerebellum it localizes to the **molecular layer/Purkinje cells** by immunostaining. | 2016 Sci Rep: https://doi.org/10.1038/srep32072 (pqac-00000000); 2023 Biomolecules review: https://doi.org/10.3390/biom13091317 (pqac-00000001, pqac-00000006); 2015 J Neurosci: https://doi.org/10.1523/JNEUROSCI.1069-15.2015 (pqac-00000004, pqac-00000007) |
| Interaction partners | IP6K3 has **noncatalytic scaffolding** interactions with **adducins** and **spectrins**; it co-immunoprecipitates with **α/β-adducin** and **α2/β2-spectrin**, and this interaction is **specific to IP6K3** versus IP6K1/2 in the cited study. It also binds **dynein intermediate chain 2 (DIC2)**; IP7 produced by IP6K3 pyrophosphorylates **DIC2 Ser51**, promoting interaction with **p150<sub>glued</sub>** and recruitment of the dynactin/dynein complex at the leading edge. | 2015 J Neurosci: https://doi.org/10.1523/JNEUROSCI.1069-15.2015 (pqac-00000004, pqac-00000005, pqac-00000007, pqac-00000008); 2023 Biomolecules review: https://doi.org/10.3390/biom13091317 (pqac-00000002) |
| Physiological roles & phenotypes | **Metabolic/aging:** Ip6k3 deletion in mice lowered blood glucose, circulating insulin, fat mass, and body weight; increased plasma lactate; improved glucose tolerance/insulin tolerance; reduced muscle **Pdk4**; and extended lifespan with reduced cardiac **S6 ribosomal protein phosphorylation**. **Neurobiology:** IP6K3 KO mice show decreased cerebellar molecular layer width, withered Purkinje dendrites, reduced Purkinje cell size/volume and spine density, impaired neuronal migration, and motor-learning/gait deficits. Quantitatively, total synapse number in cerebellum falls by about **40–50%**; specific synapses are reduced by about **40% GABAergic**, **40% parallel fiber**, and **~50% climbing fiber**; GABA synapse unit area is reduced by about **40%**. | 2016 Sci Rep: https://doi.org/10.1038/srep32072 (pqac-00000000); 2015 J Neurosci: https://doi.org/10.1523/JNEUROSCI.1069-15.2015 (pqac-00000004, pqac-00000005, pqac-00000006, pqac-00000016) |
| Therapeutic targeting & inhibitors | No IP6K3-selective therapy is established clinically, but the IP6K pathway is actively pursued pharmacologically. A 2022 probe **UNC7467** inhibited **IP6K1 8.9 nM**, **IP6K2 4.9 nM**, but was much weaker on **IP6K3 1320 nM**, showing that isoform selectivity is achievable; in cells it reduced inositol pyrophosphates by **66–81%** and improved obesity-linked metabolic phenotypes in mice. A 2023 medicinal-chemistry effort reported a brain-penetrant lead with **IC50 15 nM** and favorable brain/plasma exposure. A 2026 review summarized **SC-919** as highly potent with reported IC50s **<5.2 nM (IP6K1), <3.8 nM (IP6K2), 0.65 nM (IP6K3)**, though this is outside the user's 2023–2024 priority window. Translational 2024 work supports IP6K inhibition/5-InsP7 depletion for **cardioprotection** in myocardial ischemia–reperfusion injury, but that study was primarily **IP6K1-centered**, not IP6K3-specific. | 2022 J Med Chem: https://doi.org/10.1021/acs.jmedchem.2c00220 (pqac-00000013); 2023 inhibitor thesis summary (pqac-00000014); 2024 Cardiovasc Res: https://doi.org/10.1093/cvr/cvae017 (pqac-00000012, pqac-00000015); 2026 FEBS Lett. review for SC-919 values: https://doi.org/10.1002/1873-3468.70280 (pqac-00000011) |


*Table: This table summarizes the verified identity, enzymatic activity, localization, interaction partners, phenotypes, and therapeutic context for human IP6K3 (UniProt Q96PC2). It emphasizes experimentally supported findings and includes quantitative values and source-linked citations where available.*