Secondary Growth in Roots

In the dicot root, the vascular cambium is completely secondary in origin.

It originates from the tissue located just below the phloem bundles, a portion of pericycle tissue

TLS Online TPP Program

#Id: 9457

#XL - T Zoology

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

#XL - T Zoology

JAK kinases become activated after ligand binding and

receptor dimerization

TLS Online TPP Program

#Id: 9459

#XL - T Zoology

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

#XL - T Zoology

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

TLS Online TPP Program

#Id: 9462

#XL - T Zoology

All STAT proteins contain: 

an N-terminal DNA-binding domain

an SH2 domain

a C-terminal domain with a critical tyrosine residue

TLS Online TPP Program

#Id: 9463

#XL - T Zoology

SH2 domain (Src homology 2 domain) 

homology with a region in the Src cytosolic tyrosine kinase encoded by the src gene.