Phosphoinositide 3-kinase signalling pathways

Phosphoinositide 3-kinases (PI3Ks) phosphorylate the 3'-OH position of the inositol ring of inositol phospholipids, producing three lipid products: Pt dIns(3)P, PtdIns(3,4)P-2 and PtdIns(3,4,5)P-3. These lipids bind to the ple ckstrin homology (PH) domains of proteins and control the activity and subc ellular localisation of a diverse array of signal transduction molecules. T hree major classes of signalling molecule are regulated by binding of D-3 p hosphoinositides to PH domains: guanine-nucleotide-exchange proteins for Rh o family GTPases, the TEC family tyrosine kinases such as BTK and ITK in B and T lymphocytes, respectively, and the AGC superfamily of serine/threonin e protein kinases, These molecules are activated by a variety of extracellu lar stimuli and have been implicated in a wide range of cellular processes, including cell cycle progression, cell growth, cell motility, cell adhesio n and cell survival.