Polycomb or Pc-G proteins do not initiate repression, but they are responsible for maintaining it.

TLS Online TPP Program

#Id: 9663

#Unit 4. Cell Communication and Cell Signaling

Kinase activity associated with receptor activation phosphorylates tyrosines on the bound PLCγ, enhancing its hydrolase activity. 

TLS Online TPP Program

#Id: 9664

#Unit 4. Cell Communication and Cell Signaling

Activated RTKs and cytokine receptors initiate another phosphoinositide pathway by recruiting PI-3 kinase to the cytosolic surface of the plasma membrane.

TLS Online TPP Program

#Id: 9665

#Unit 4. Cell Communication and Cell Signaling

PI-3 kinase contains SH2 domain which binds to phosphotyrosines on the activated RTKs and cytokine receptors

TLS Online TPP Program

#Id: 9666

#Unit 4. Cell Communication and Cell Signaling

PI-3 kinase adds a phosphate to the 3′ carbon in one of two separate PI substrates, leading to formation of two PI 3-phosphates: PI(3,4)P2 or PI(3,4,5)P3

TLS Online TPP Program

#Id: 9667

#Unit 4. Cell Communication and Cell Signaling

In cells, PI-3 kinase pathway :

Triggers cell division 

Prevents apoptosis

Induces specific changes in cell metabolism

TLS Online TPP Program

#Id: 9668

#Unit 4. Cell Communication and Cell Signaling

An important signal transduction protein that binds to PI 3-phosphates is protein kinase B (Akt),  a serine/threonine kinase