Which one or more of the following statements is/are correct regarding the transport and retention of proteins in different cell organelles?
Which one or more of the following statements is/are correct regarding the transport and retention of proteins in different cell organelles?
(A) Mannose 6-phosphate residues are involved in targeting proteins to lysosomes.
(B) Transport of proteins into the mitochondrial compartment is aided by positively charged amino acid residues at the N-terminus and internal hydrophobic segments.
(C) The retention of protein in the ER lumen requires the KDEL sequence motif at the C-terminus.
(D) Nuclear proteins are transported in an unfolded conformation and the nuclear localization signal sequence is subsequently cleaved by peptidases in the nucleoplasm.
Answered
Answer: (A) Mannose 6-phosphate residues are involved in targeting proteins to lysosomes.
(C) The retention of protein in the ER lumen requires the KDEL sequence motif at the C-terminus.
Explanation:
- Mannose 6-phosphate is a marker for lysosomal targeting.
- The KDEL sequence retains proteins within the ER.
- Nuclear proteins are typically transported in their folded form, and the nuclear localization signal is usually not cleaved.
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