The retina organized into layers: Outer nuclear layer contains the photoreceptors , rods & cones 

Inner nuclear layer contains the cell bodies of excitatory and

inhibitory interneurons including bipolar cells, horizontal cells, & amacrine cells

TLS Online TPP Program

#Id: 1360

#Unit 4. Cell Communication and Cell Signaling

Receptor Homodimerization GH, prolactin, G-CSF, thrombopoietin, and Epo have similar structures & they activate receptors of similar structure by forming dimers of two identical cytokine receptor proteins.

 

TLS Online TPP Program

#Id: 1361

#Unit 4. Cell Communication and Cell Signaling

Cytokine receptors activate tyrosine kinases in which receptor and kinase are separate polypeptides.

TLS Online TPP Program

#Id: 1362

#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: 1363

#Unit 4. Cell Communication and Cell Signaling

JAK kinases become activated after ligand binding and receptor dimerization.

TLS Online TPP Program

#Id: 1364

#Unit 4. Cell Communication and Cell Signaling

Phosphorylation of the activation loop leads to a conformational change in the JAK kinase that enhances the affinity of the enzyme for ATP & increasing kinase activity.

TLS Online TPP Program

#Id: 1365

#Unit 4. Cell Communication and Cell Signaling

JAK kinases phosphorylate several tyrosine residues on the cytosolic domain of the cytokine receptor.