Glycosylphosphatidylinositol anchors are added to proteins: on the C-terminus af
ID: 56472 • Letter: G
Question
Glycosylphosphatidylinositol anchors are added to proteins:
on the C-terminus after translation into the E.R. via a SRP-SRP receptor mechanism
on the C-terminus following translation in the cytoplasm via a SRP-SRP receptor independent mechanism
on the C-terminus by BIP
that are localized within the nuclear envelope
on the C-terminus after translation into the E.R. via a SRP-SRP receptor mechanism
on the C-terminus following translation in the cytoplasm via a SRP-SRP receptor independent mechanism
on the C-terminus by BIP
that are localized within the nuclear envelope
Explanation / Answer
Glycosylphosphatidylinositol is a glycolipid, which is attached to protein at C-terminus during post-translational modification. The signal sequence is associated with GPI-linked proteins, which directs the protein to ER. The protein inserted into the ER is attached to ER membrane by hydrophobic C terminus.
The proteins are synthesized on free cytosolic ribosomes and their posttranslational modifications occur in ER. Thus, the proteins are incorporated into the ER. The incorporation of protein requires simple signal sequences and certain chaperones in the ER such as BiP but does not require SRP. The BiP pulls the polypeptide chain into the ER through the channel. Thus, the binding of polypeptide chains to BiP is needed to drive the posttranslational translocation of proteins into the ER. In contrast, the co-translational translocation of growing polypeptide chains is driven directly by the process of protein synthesis.
Hence, the correct option among the following is 3rd- on the C-terminus by BIP.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.