【多选题】How do receptor tyrosine kinases (RTKs) activate the PI-3-kinase–Akt signaling pathway?
A.
An extracellular survival signal, such as IGF, activates an RTK, which recruits and activates PI 3-kinase. PI 3-kinase then phosphorylates an inositol phospholipid that is embedded in the cytosolic side of the plasma membrane.
B.
The resulting phosphorylated inositol phospholipid attracts intracellular signaling proteins that have a special domain that recognizes it.
C.
One of these signaling proteins, Akt, is a protein kinase that is activated at the membrane by phosphorylation mediated by two other protein kinases (here called protein kinases 1 and 2); protein kinase 1 is also recruited by the phosphorylated lipid docking sites.
D.
Once activated, Akt is released from the plasma membrane and phosphorylates various downstream proteins on specific serines and threonines.