The GTPase Dynamin is involved in which step of vesicular trafficking A) Binding

Question

The GTPase Dynamin is involved in which step of vesicular trafficking A) Binding of cargo molecules to cargo receptors B) Assembly of the Clathrin cost C) Pinching off the vesicle from the membrane D) Transport of vesicles along microtubules Which of the following events does not occur in the rough endoplasmic reticulum? A) Cleavage of the signal peptide by the signal peptidase B) Binding of chaperone proteins to misfolded or partially folded pathways C) Transfer of pre formed oligosaccharide to a new polypeptide by oligosaccharyl transfera... D) Degradation of misfoled proteins by the ubiquitin proteasome system E) Formation of vesicles destined for the Golgi apparatus Which of the following elements is not required for transport of a soluble protein into the lumen A) ER signal sequence B) Protein translocator C) Signal recognition particle receptor D) Stop transfer sequence

Explanation / Answer

1. A, B, C . In vesicular transport a vesicle is formed by budding of the membrane. The cytoplasmic surfaces of transport vesicles are coated with proteins, . Three kinds of coated vesicles, a.it is clathrin-coated vesicles carry the uptake of extracellular molecules from the plasma membrane by endocytosis and also the transport of molecules from the trans Golgi network to lysosome . b) nonclathrin-coated or COP-coated vesicles (COP stands for coat protein). COPII-coated vesicles) bud from the ER and carry their cargo forward along the secretory pathway, to the Golgi apparatus where as COPI-coated vesicles bud from the ER-Golgi intermediate compartment or the Golgi appar tus GTP ase is dynamin protein carry out GTP HYDROLYSIS

sequences of bases in the RNA to an amino acid sequence that will constitute a protein.

2. D is correct does not take place The peptide consists of a "signal sequence" that binds to a signal recognition particle (SRP) from the cytoplasm. The SRP is as a guide and essential for protein translocation into the rER lumen The cytoplasmic surface of the rER contains a protein called the SRP receptor that binds to the SRP. In the translation , the peptide is move into the lumen of the rER so,the signal sequence is cut off for post-translational modifications

Proteins change their shape by the addition of carbohydrates (glycosylation) to specific amino acids in thpeptide chain. ex oligosaccharide ( oligo means "few"; saccharide means "sugar" or "carbohydrate") is added to the growing peptide. The branched oligosaccharide is consistof three sugars: glucose, mannose, and N-acetylglucosamine changed in the rER and, later, in the Golgi complex.

3.B signal sequence of ribosome is recognized by the SRP which escorts the complex to the membrane of ER and here it binds to the SRP receptor where translation carried out growing polypeptide chain is transclocated across the membrane ,cleavage of the signal sequence by signal peptidase releases the polypeptide into the ER lumen The STOP TRANSFER SIGNAL stops the transfer of growing polypeptide (a sequence of non polar aminoacids)   

4. A&B

5.B

6.B. SIGNAL SEQUENCE is a short sequence of 15-35 amino acids at the N.terminus of the growing poly peptide chain invoved in the synthesiss of secretory protiens targeted to the ER by SR

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