The two β pleated sheets in each domain are held together by hydrophobic interactions and the conserved disulfide bond.  The three loops of each variable domain show considerable variation in length and amino acid sequence; these hyper variable regions  make up the antigen-binding site. 

TLS Online TPP Program

#Id: 10320

#Unit 4. Cell Communication and Cell Signaling

The tumor cells may acquire additional oncogenic mutations that allow them to escape the immune system.

TLS Online TPP Program

#Id: 10321

#Unit 4. Cell Communication and Cell Signaling

The tumor down regulates the expression of class I MHC proteins

TLS Online TPP Program

#Id: 10322

#Unit 4. Cell Communication and Cell Signaling

Sometimes the tumor cells up-regulate the expression of anti-apoptotic proteins like BCL-2.

TLS Online TPP Program

#Id: 10323

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 10324

#Unit 4. Cell Communication and Cell Signaling

PD-1 has a structure similar to CTLA-4 and when activated negatively regulates T-cell function by inducing apoptosis of activated T cells. 

TLS Online TPP Program

#Id: 10325

#Unit 4. Cell Communication and Cell Signaling

Monoclonal Antibodies Against Immune Checkpoint Molecules to Treat Cancers