A third fate that can befall a duplicated gene is neofunctionalization. Here the duplicate evolves a novel biological function. 

TLS Online TPP Program

#Id: 7944

#Section 3: Genetics, Cellular and Molecular Biology

Membrane and soluble secretory proteins synthesized on the rough ER undergo four principal modifications before they reach their final destinations: 

(1) Glycosylation in the ER and Golgi complex

(2) Formation of disulfide bonds in the ER

(3) Proper folding of polypeptide chains and assembly of multisubunit proteins in the ER

(4) Specific proteolytic cleavages in the ER, Golgi complex, and secretory vesicles

TLS Online TPP Program

#Id: 7943

#Section 3: Genetics, Cellular and Molecular Biology

Classes of ER membrane proteins

TLS Online TPP Program

#Id: 7942

#Section 3: Genetics, Cellular and Molecular Biology

TLS Online TPP Program

#Id: 7941

#Section 3: Genetics, Cellular and Molecular Biology

The translocon was first identified through mutations in the yeast gene encoding a protein called Sec61α

TLS Online TPP Program

#Id: 7940

#Section 3: Genetics, Cellular and Molecular Biology

Once the SRP and its receptor have targeted a ribosome synthesizing a secretory protein to the ER membrane, the ribosome and nascent polypeptide chain are rapidly transferred to the translocon.

TLS Online TPP Program

#Id: 7939

#Section 3: Genetics, Cellular and Molecular Biology

The GTPase cycle analogous to the GTP hydrolysis coupled to the initiation of translation on the ribosome.