1.) What are the functions of the signal recognition particle (SRP) during the p

Question

1.) What are the functions of the signal recognition particle (SRP) during the protein translocation into the ER?

2.) List at least two well studied protein coats and give an example of the vesicle formation that is mediated by each of these coats proteins?

3.) Which amino acid(s) is the target for the N-linked glycosylation? Where does the N-linked glycosylation occur?

4.) Is the statement "Once a secretory vesicle is properly positioned beneath the plasma membrane, it will immadietly fuse with the membrane and release its contents to the cell exterior" correct? Please explain your answer.

5.) How does lysosome maintain the lumen at a low pH?

Explanation / Answer

1) Only with the help of signal peptide, the secreted proteins are targeted to their respective organelles or to extracellular space. Binding of signal recognition particle (SRP) to the signal peptide allows it to bind to the (SRP) receptor of endoplasmic reticulum after translation of protein.

3) Asparagine (Asn) is the target for N-linked glycosylation and it takes place in Endoplasmic reticulum.

4) Its incorrect. There are two pathways, one is Ca2+ triggered non-constitutive which requires increase in intracellular calcium levels to fuse and release secreted products outside the plasma membrane. And the other is non-Ca2+ triggered constitutive which is not regulated and that fuses with plasma membrane to delivery membrane proteins and other components of plasma membrane.

5) Lysosome maintain the lumen at low pH (Acidic) by actively transporting protons (H+) from the cytosol to its lumen through proton pump present in the lysosomal membrane.

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