Regeneration blastema forms from pluripotent stem cells called clonogenic neoblasts (cNeoblasts).

TLS Online TPP Program

#Id: 9637

#Unit 4. Cell Communication and Cell Signaling

GRB2 is an adapter protein, serves as a link, or scaffold, between the activated receptor and Sos

TLS Online TPP Program

#Id: 9638

#Unit 4. Cell Communication and Cell Signaling

Sos is a GEF that catalyzes conversion of inactive GDP bound Ras to the active GTP-bound form.

TLS Online TPP Program

#Id: 9639

#Unit 4. Cell Communication and Cell Signaling

GRB2 has- 

Phosphotyrosine-binding SH2 domain

Two SH3 domains, bind to Sos

TLS Online TPP Program

#Id: 9640

#Unit 4. Cell Communication and Cell Signaling

The SH3 domains in GRB2 selectively bind to 

proline-rich sequences in Sos

TLS Online TPP Program

#Id: 9641

#Unit 4. Cell Communication and Cell Signaling

Downstream of Ras is a highly conserved cascade of three protein kinases-

Ras → Raf → MEK → MAP kinase

TLS Online TPP Program

#Id: 9642

#Unit 4. Cell Communication and Cell Signaling

In unstimulated cells, 

Raf is phosphorylated by several cytosolic kinases on two sites:

1. Serine/threonine kinase domain 

2. N-terminal autoinhibitory domain