Find correct order of cotranslational translocation in endoplasmic reticulum

A. Transfer of the nascent polypeptide–ribosome to the translocon leads to opening of this

translocation channel to admit the growing polypeptide adjacent to the signal sequence, which is transferred to a hydrophobic binding site next to the central pore. Both the SRP and SRP receptor, once dissociated from the translocon, hydrolyze their bound GTP and then are ready to initiate the insertion of another polypeptide chain.

B. As the polypeptide chain elongates, it passes through the translocon channel into the ER lumen, where the signal sequence is cleaved by signal peptidase and is rapidly degraded.

C. The SRP and the nascent polypeptide chain–ribosome complex bind to the SRP receptor in

the ER membrane. This interaction is strengthened by the binding of GTP to both the SRP and its receptor.

D. The ER signal sequence emerges from the ribosome; it is bound by a signal recognition particle (SRP).

TLS Online TPP Program

#Question id: 28698

#Unit 2. Cellular Organization

the oligosaccharide precursor is assembled on a membrane- attached anchor called dolichol phosphate, which is___

TLS Online TPP Program

#Question id: 28699

#Unit 2. Cellular Organization

First sugar residue is attached to dolichol by ___

TLS Online TPP Program

#Question id: 28700

#Unit 2. Cellular Organization

Biosynthesis of all N-linked oligosaccharides begins in the rough ER with a preformed branched oligosaccharide precursor Glc3Man9(GlcNAc)2, Which of the following statements is incorrect about these biosynthesis?

a) the oligosaccharide precursor is assembled on a membrane- attached anchor called dolichol phosphate

b) First sugar residue is attached to dolichol by a glycosidic bonds & the other

sugars are added by high-energy pyrophosphate

c) Two N- acetylglucosamine (GlcNAc) and five mannose residues are added one at a time to a dolichol phosphate on the lumen

d) Four mannose and three glucose  residue are added one to a dolichol phosphate on the luminal side

TLS Online TPP Program

#Question id: 28701

#Unit 2. Cellular Organization

Which of the following inhibitors inhibits the synthesis of all N-linked oligosaccharides in cells?

TLS Online TPP Program

#Question id: 28702

#Unit 2. Cellular Organization

Oligosaccharyl transferase enzyme involves to transferred precursor oligosaccharide 

TLS Online TPP Program

#Question id: 28703

#Unit 2. Cellular Organization

Oligosaccharyl transferase enzyme involves to transferred precursor oligosaccharide from a dolichol lipid anchor to the tripeptide sequences, which of the following tripeptide sequences are substrates for oligosaccharyl transferase ?