Following binding of an EGF ligand, the rate of endocytosis of HER1 is increased about tenfold, and only a fraction of the internalized receptors return to the plasma membrane; the rest are degraded in lysosomes.

TLS Online TPP Program

#Id: 7792

#Unit 2. Cellular Organization

Ran is a small monomeric G protein

That exists in either a GTP-bound or a GDP-bound conformation & provides the energy to drive unidirectional transport of macromolecules through the nuclear pore.

TLS Online TPP Program

#Id: 7793

#Unit 2. Cellular Organization

Nuclear-export signal (NES)

ribonuclear protein complexes that shuttle between the nucleus and the cytoplasm. Such shuttling proteins contain NES.

TLS Online TPP Program

#Id: 7794

#Unit 2. Cellular Organization

Shuttling protein have identified at least three different types of NESs: 

A. A leucine-rich sequence found in PKI 

B. In the Rev protein of human immunodeficiency virus (HIV)

C. In two heterogeneous ribonucleoprotein particles (hnRNPs)

TLS Online TPP Program

#Id: 7795

#Unit 2. Cellular Organization

Nuclear export mechanism are of two types:

Ran-dependent nuclear export

Ran-independent nuclear export

TLS Online TPP Program

#Id: 7796

#Unit 2. Cellular Organization

Ran dependent mechanism for nuclear export of cargo proteins containing a leucine-rich nuclear-export signal (NES).

TLS Online TPP Program

#Id: 7797

#Unit 2. Cellular Organization

Exportin 1

a specific nuclear transport receptor for export mechanism