Pathways & interactions
PI3K p85 subunit (IPR001720)
Short name: PI3kinase_P85
Protein phosphorylation, which plays a key role in most cellular activities, is a reversible process mediated by protein kinases and phosphoprotein phosphatases. Protein kinases catalyse the transfer of the gamma phosphate from nucleotide triphosphates (often ATP) to one or more amino acid residues in a protein substrate side chain, resulting in a conformational change affecting protein function. Phosphoprotein phosphatases catalyse the reverse process. Protein kinases fall into three broad classes, characterised with respect to substrate specificity [PMID: 3291115]:
- Serine/threonine-protein kinases
- Tyrosine-protein kinases
- Dual specificity protein kinases (e.g. MEK - phosphorylates both Thr and Tyr on target proteins)
Protein kinase function is evolutionarily conserved from Escherichia coli to human [PMID: 12471243]. Protein kinases play a role in a multitude of cellular processes, including division, proliferation, apoptosis, and differentiation [PMID: 12368087]. Phosphorylation usually results in a functional change of the target protein by changing enzyme activity, cellular location, or association with other proteins. The catalytic subunits of protein kinases are highly conserved, and several structures have been solved [PMID: 15078142], leading to large screens to develop kinase-specific inhibitors for the treatments of a number of diseases [PMID: 15320712].
PI3 kinases are enzymes that phosphorylate phosphoinositides on the 3-hydroxyl group of the inositol ring. The precise functions of the three products of PI3 kinase (PI-3-P, PI-3,4-P and PI-3,4,5-P) are not yet known, but it is suggested that they function as second messengers in signal transduction events in organisms ranging from yeast to mammals. There are several forms of PI3 kinase. One of these is the mammalian enzyme, a heterodimer of a 110 kDa catalytic subunit and an 85 kDa regulatory subunit, which allows it to bind to activated tyrosine protein kinases. PI3 kinase P85 alpha subunits contain an N-terminal SH3 domain, and two SH2 domains in the C-terminal half of the sequence [PMID: 1707345, PMID: 1849460].
- PTHR10155 (PTHR10155)