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Phosphatidylinositol kinases C

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


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Phosphatidylinositol may be phosphorylated at either 3- or 4- positions on the inositol ring by PI 3-kinases or PI 4-kinases, respectively.

Phosphatidylinositol 3-kinases

Phosphatidylinositol 3-kinases (PI3K, provisional nomenclature) catalyse the introduction of a phosphate into the 3-position of phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP) or phosphatidylinositol 4,5-bisphosphate (PIP2). There is evidence that PI3K can also phosphorylate serine/threonine residues on proteins. In addition to the classes described below, further serine/threonine protein kinases, including ATM (Q13315) and mTOR (P42345), have been described to phosphorylate phosphatidylinositol and have been termed PI3K-related kinases. Structurally, PI3Ks have common motifs of at least one C2, calcium-binding domain and helical domains, alongside structurally-conserved catalytic domains. Wortmannin and LY 294002 are widely-used inhibitors of PI3K activities. Wortmannin is irreversible and shows modest selectivity between Class I and Class II PI3K, while LY294002 is reversible and selective for Class I compared to Class II PI3K.

Class I PI3Ks (EC phosphorylate phosphatidylinositol 4,5-bisphosphate to generate phosphatidylinositol 3,4,5-trisphosphate and are heterodimeric, matching catalytic and regulatory subunits. Class IA PI3Ks include p110α, p110β and p110δ catalytic subunits, with predominantly p85 and p55 regulatory subunits. The single catalytic subunit that forms Class IB PI3K is p110γ. Class IA PI3Ks are more associated with receptor tyrosine kinase pathways, while the Class IB PI3K is linked more with GPCR signalling.

Class II PI3Ks (EC phosphorylate phosphatidylinositol to generate phosphatidylinositol 3-phosphate (and possibly phosphatidylinositol 4-phosphate to generate phosphatidylinositol 3,4-bisphosphate). Three monomeric members exist, PI3K-C2α, β and β, and include Ras-binding, Phox homology and two C2domains.

The only class III PI3K isoform (EC is a heterodimer formed of a catalytic subunit (VPS34) and regulatory subunit (VPS15).

Phosphatidylinositol 4-kinases

Phosphatidylinositol 4-kinases (EC generate phosphatidylinositol 4-phosphate and may be divided into higher molecular weight type III and lower molecular weight type II forms.


PI3Kα (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) C Show summary » More detailed page

PI4KIIIα/PIK4CA (phosphatidylinositol 4-kinase alpha) C Show summary » More detailed page

PI3Kβ (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta) C Show summary » More detailed page

PI4KIIIβ/PIK4CB (phosphatidylinositol 4-kinase beta) C Show summary » More detailed page

PI4KIIα/PI4K2A (phosphatidylinositol 4-kinase type 2 alpha) C Show summary »

PI3Kγ (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma) C Show summary » More detailed page

PI3Kδ (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta) C Show summary » More detailed page

PI4KIIβ/PI4K2B (phosphatidylinositol 4-kinase type 2 beta) C Show summary »

p85α/PIK3R1 (phosphoinositide-3-kinase regulatory subunit 1) Show summary » More detailed page

p85β/PIK3R2 (phosphoinositide-3-kinase regulatory subunit 2) Show summary » More detailed page

p55γ/PIK3R3 (phosphoinositide-3-kinase regulatory subunit 3) Show summary »

p150/VPS15/PIK3R4 (phosphoinositide-3-kinase regulatory subunit 4) Show summary » More detailed page

p101/PIK3R5 (phosphoinositide-3-kinase regulatory subunit 5) Show summary »

p87/PIK3R6 (phosphoinositide-3-kinase regulatory subunit 6) Show summary »

C2α/PIK3C2A (phosphatidylinositol-4-phosphate 3-kinase catalytic subunit type 2 alpha) C Show summary » More detailed page

C2β/PIK3C2B (phosphatidylinositol-4-phosphate 3-kinase catalytic subunit type 2 beta) C Show summary » More detailed page

C2γ/PIK3C2G (phosphatidylinositol-4-phosphate 3-kinase catalytic subunit type 2 gamma) C Show summary » More detailed page

VPS34 (phosphatidylinositol 3-kinase catalytic subunit type 3) C Show summary » More detailed page


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Further reading

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NC-IUPHAR subcommittee and family contributors

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How to cite this family page

Database page citation (select format):

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Fabbro D, Kelly E, Mathie A, Peters JA, Veale EL, Armstrong JF, Faccenda E, Harding SD, Pawson AJ, Sharman JL, Southan C, Davies JA; CGTP Collaborators. (2019) The Concise Guide to PHARMACOLOGY 2019/20: Enzymes. Br J Pharmacol. 176 Issue S1: S297-S396.