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

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 coat C) pinching off of 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 proteins C) Transfer of a pre-formed oligosaccharide to a new polypeptide by oligosaccharyl D) Degradation of misfolded 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 endoplasmic reticulum (ER)? A) ER signal sequence b) protein translator C) signal recognition particle receptor D) stop transfer sequence Your friend works in a biotechnology company and has discovered a drug

Explanation / Answer

1. The GTPase dynamin is involved in the eukaryotic cell endocytosis processes. They are principally involved in scission of newly formed vesicles from the membrane. It transfers them to another membrane, for example of a vesicle is a clathrin-coated pit. B) Assembly of the clathrin coat is the right answer choice.

2. Rough ER gets the polypeptide from the ribosome attached, next step is to forms the glycoprotein with the help of sugar coatings, then forms a transfer vesicle to bus off, then its buds out as the secondary glycoprotein inside of it gets in, later transferred to Golgi body. A) Signal peptidases are present in RER, B) Chaperons are also present in RER and help in membrane transport, also, they are present in ribosomes, C) and D) also represents and are placed in RER,

Now from the options above we can eliminate/ or the processes that does not occur here are: A) Here the signal peptide which is about 16-30 amino acids long, present at the N-terminus of the majority of newly synthesized proteins, does it work away from the rough ER, this option we can eliminate.

3. Transport of soluble proteins into the lumen of ER: C) Signal recognition particle receptor also called docking protein is exclusively found in the rough ER of mammalian cells, B) Translocator protein are also present in the membrane surface of rough ER,

Only the D) Stop transfer sequence does not require in the process,

4. Importins and exportins are the special molecules, they are helped by the small Ras related GTPase, Ran to transport their cargo. C) Nuclear transport receptors would be unable to release their cargo in the nucleus.

5. The sequential process is this way,

First the Cargo receptor binds to cargo molecules,

Next, Clathrin and adaptin binds to each other along with the cargo receptor,

Later on dynamin pushes off the whole setup from the cell membrane,

Later the whole vesicle releases the clathrin coating,

So, here the answer choice will be D) IV -- II -- I -- III.

6. Signal sequences that direct proteins to the ER are - B) Added to the protein by a protein translocator.

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