Class I PI 3-kinases are a subgroup of the enzyme family,
phosphoinositide 3-kinase that possess a common protein domain structure, substrate specificity, and method of activation. Class I PI 3-kinases are further divided into two subclasses, class IA PI 3-kinases and class IB PI 3-kinases.
Class IA PI 3-kinases
Class IA PI 3-kinases are activated by
receptor tyrosine kinases
Receptor tyrosine kinases (RTKs) are the high- affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinas ...
(RTKs).
There are three catalytic subunits that are classified as class IA PI 3-kinases:
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p110α
The phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (the HUGO-approved official symbol = PIK3CA; HGNC ID, HGNC:8975), also called p110α protein, is a class I PI 3-kinase catalytic subunit. The human p110α protein is enc ...
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p110β
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p110δ
Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta isoform also known as phosphoinositide 3-kinase (PI3K) delta isoform or p110δ is an enzyme that in humans is encoded by the ''PIK3CD'' gene.
p110δ regulates immune function. ...
There are currently five regulatory subunits that are known to associate with class IA PI 3-kinases catalytic subunits:
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p85α
Phosphatidylinositol 3-kinase regulatory subunit alpha is an enzyme that in humans is encoded by the ''PIK3R1'' gene.
Function
Phosphatidylinositol 3-kinase phosphorylates the inositol ring of phosphatidylinositol at the 3-prime position. The ...
and
p85β
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p55α and
p55γ
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p50α
Class IB PI 3-kinases
Class IB PI 3-kinases are activated by
G-protein-coupled receptors
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
(GPCRs).
The only known class IB PI 3-kinase catalytic subunit is
p110γ.
There are two known regulatory subunits for p110γ:
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p101
*p84/
p87PIKAP
Within molecular biology, molecular and cell biology, p87PIKAP is a regulatory subunit of the type IB Phosphoinositide 3-Kinase p110γ that is highly expressed in the heart and is present in dendritic cells, macrophages, and neutrophils.
It is als ...
.
See also
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Phosphoinositide 3-kinase#Class I
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Phosphoinositide 3-kinase inhibitor
Phosphoinositide 3-kinase inhibitors (PI3K inhibitors) are a class of medical drugs that are mainly used to treat advanced cancers. They function by inhibiting one or more of the phosphoinositide 3-kinase (PI3K) enzymes, which are part of the P ...
References
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EC 2.7.1
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