Phosphatidylinositol 3-kinases (PI3Ks) are lipid kinases that phosphorylate
4,5-bisphonate (PI(4,5) P2 or PIP2) at the 3-position of the inositol ring,
and thus generate phosphatidylinositol 3,4,5-trisphosphate (PIP3), which, in
turns, initiates a vast array of signaling events. PI3Ks can be grouped into
three classes based on their domain organization. Class I PI3Ks are
heterodimers consisting of a p110 catalytic subunit and a regulatory subunit
of either the p85 type (associated with the class IA p110 isoforms p110α,
p110β or p110delta) or the p101 type (associated with the class IB p110
isoform p110γ). Common to all catalytic subunits are the N-terminal
adaptor-binding domain (ABD) (see <PDOC51544>) that binds to p85, the Ras-binding domain (RBD), the putative membrane-binding domain (C2), the helical
domain of unknown function, and the kinase catalytic domain (see <PDOC00710>).
Class II PI3Ks lack the ABD domain and are distinguished by a carboxy terminal
C2 domain (see <PDOC00380>). Class III enzymes lack the ABD and RBD domains
The PI3K C2 domain is an eight-stranded antiparallel β-sandwich consisting
of two four-stranded β-sheets (see <PDB:1E8X>) [1,2,3,4].
The profile we developed covers the entire PI3K C2 domain.
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