P110α

P110α is a catalytic subunit of the enzyme phosphoinositide 3-kinase (PI3K). It is encoded by the gene PIK3CA in humans. P110α plays a crucial role in the cell signaling pathway and is involved in various cellular functions such as cell growth, cell proliferation, cell differentiation, cell survival, intracellular trafficking, and cell migration.

Structure

P110α is a 110 kDa protein that is composed of 1068 amino acids. It has five domains: an adaptor-binding domain, a Ras-binding domain, a C2 domain, a helical domain, and a kinase domain. The kinase domain is responsible for the enzyme's catalytic activity.

Function

P110α, together with the regulatory subunit p85, forms the class IA PI3Ks. These enzymes are activated by receptor tyrosine kinases (RTKs) and G-protein coupled receptors (GPCRs). Upon activation, PI3K phosphorylates phosphatidylinositol 4,5-bisphosphate (PIP2) to produce phosphatidylinositol 3,4,5-trisphosphate (PIP3). PIP3 acts as a second messenger that initiates a series of downstream signaling events, leading to the activation of Akt and mTOR pathways. These pathways regulate various cellular processes, including cell growth, proliferation, survival, and migration.

Clinical significance

Mutations in the PIK3CA gene that encodes P110α are frequently found in various types of cancer, including breast cancer, colorectal cancer, and lung cancer. These mutations often result in the constitutive activation of PI3K, leading to uncontrolled cell growth and proliferation. Therefore, P110α is considered a potential therapeutic target for cancer treatment.

See also

• Phosphoinositide 3-kinase
• PIK3CA
• Cell signaling
• Cancer