The tRNAAla structural elements recognized by then Ala-tRNA synthetase are unusually simple.  A single G=U base pair 3:70 is the only element needed for specific binding and aminoacylation

TLS Online TPP Program

#Id: 9451

#Unit 4. Cell Communication and Cell Signaling

The extracellular domain of cytokine receptors are constructed of two subdomains, each contains seven conserved β strands folded together

TLS Online TPP Program

#Id: 9452

#Unit 4. Cell Communication and Cell Signaling

In cytokine receptors, 

the receptor and kinase are separate polypeptides, encoded by different genes, yet are bound tightly together.

TLS Online TPP Program

#Id: 9454

#Unit 4. Cell Communication and Cell Signaling

In cytokine receptors, the tightly bound kinase is known as a JAK kinase.

TLS Online TPP Program

#Id: 9455

#Unit 4. Cell Communication and Cell Signaling

Cytokine receptors are stably associated with one or two of the four known JAKs:

JAK1, JAK2, JAK3, and Tyk2

TLS Online TPP Program

#Id: 9457

#Unit 4. Cell Communication and Cell Signaling

Each members of JAK family of kinases contains:

An N-terminal domain that binds to the receptor

A C-terminal kinase domain 

A middle pseudokinase domain

TLS Online TPP Program

#Id: 9458

#Unit 4. Cell Communication and Cell Signaling

JAK kinases become activated after ligand binding and

receptor dimerization