The addition of the 3’-CCA is catalyzed by the enzyme tRNA nucleotidyltransferase, which functions as a nontemplate-directed RNA polymerase.

TLS Online TPP Program

#Id: 9610

#Unit 4. Cell Communication and Cell Signaling

Insulin receptor, form disulfide-linked dimers in the absence of hormone.

TLS Online TPP Program

#Id: 9611

#Unit 4. Cell Communication and Cell Signaling

Binding of ligand to predimerized but inactive RTK alters the conformation of the dimer in such a way that the receptor’s kinase becomes activated.

TLS Online TPP Program

#Id: 9612

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9613

#Unit 4. Cell Communication and Cell Signaling

In the absence of insulin, the extracellular domain adopts a symmetric inverted U-shaped conformation. 

TLS Online TPP Program

#Id: 9614

#Unit 4. Cell Communication and Cell Signaling

Upon insulin binding, the extracellular domain is converted into a T-shaped conformation that brings the transmembrane domains together.

TLS Online TPP Program

#Id: 9615

#Unit 4. Cell Communication and Cell Signaling

Four related EGF receptors participate in signaling by the many members of EGF family :

In the mouse - Erb-B1, 2, 3, and 4

In humans - HER 1, 2, 3, and 4