In mammals

XIAP (inhibitor of apoptosis proteins) restrain both initiator and effector caspases

TLS Online TPP Program

#Id: 1369

#Unit 4. Cell Communication and Cell Signaling

The SH2 domain binds strongly to a critical four-residue core sequence containing peptide:  Phosphotyrosine–glutamic acid–glutamic acid–isoleucine

TLS Online TPP Program

#Id: 1370

#Unit 4. Cell Communication and Cell Signaling

Binding resembles the insertion of a two-pronged “plug”—the phosphotyrosine and isoleucine side chains of the peptide—into a two-pronged “socket” in the SH2 domain.

TLS Online TPP Program

#Id: 1371

#Unit 4. Cell Communication and Cell Signaling

The receptor for erythropoietin, GH, prolactin, G-CSF, activates STAT5 (but not STATs 1, 2, 3, or 4)

TLS Online TPP Program

#Id: 1372

#Unit 4. Cell Communication and Cell Signaling

STAT homodimer has two phosphotyrosine-SH2 domain interactions

TLS Online TPP Program

#Id: 1373

#Unit 4. Cell Communication and Cell Signaling

 Phosphorylated STAT dissociates spontaneously from the receptor, dimerize & move into the nucleus.

 

TLS Online TPP Program

#Id: 1374

#Unit 4. Cell Communication and Cell Signaling

Erythropoietin,

• secreted by kidney cells

• promotes proliferation and differentiation of erythroid progenitor cells in the bone marrow to increase the number of mature red cells in the blood