Tropical rain forest

 Rainfall exceeds 230 cm per year, and temperature is hot year-round, averaging 25 to 29C. 

 Tropical rainforests lie in a band around the equator within the tropics of Cancer and Capricorn (23.5° N and S). 

 Soils are commonly shallow and nutrient-poor

There is little seasonal variation in sunlight and temperature

Tropical rainforests are produced 40 per cent of NPP of terrestrial ecosystems.

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

TLS Online TPP Program

#Id: 9459

#Unit 4. Cell Communication and Cell Signaling

Ligand binding triggers a conformational change in the JAKs & they phosphorylate each other on a critical tyrosine in the activation loop which greatly enhances kinase activity

TLS Online TPP Program

#Id: 9461

#Unit 4. Cell Communication and Cell Signaling

Active JAK kinase phosphorylates several tyrosine residues in the receptor’s cytosolic domain and activates a STAT transcription factor that moves directly to the nucleus