Question

Sort the following events as they occur during the peroxisomal protein import cycle, starting with the release of cargo from Pex5. Your answer would be a five-letter string composed of letters A to E only, e.g. ABEDC.

(A) Pex5 deubiquitylation
(B) Pex5 ubiquitylation
(C) Docking and translocation of the cargo protein along with Pex5
(D) Pex5 export from the peroxisome with the help of ATPases Pex1 and Pex6
(E) Pex5 binding to a cargo protein containing a C-terminal peroxisomal targeting sequence

Answer 1

The correct order after the release of cargo from Pex5 during the peroxisomal protein import cycle is CEBDA, which includes docking/translocation, binding to protein, ubiquitylation, export, and finally deubiquitylation of Pex5.

Step-by-step explanation:

The student is asking about the sequence of events that occur during the peroxisomal protein import cycle. When Pex5 releases its cargo, a specific series of steps must follow to complete the cycle. To reorder the provided steps into their correct sequential order, starting with the release of cargo from Pex5, we look at the known process of protein translocation into peroxisomes. The correct sequence would be:

1. (C) Docking and translocation of the cargo protein along with Pex5.
2. (E) Pex5 binding to a cargo protein containing a C-terminal peroxisomal targeting sequence.
3. (B) Pex5 ubiquitylation.
4. (D) Pex5 export from the peroxisome with the help of ATPases Pex1 and Pex6.
5. (A) Pex5 deubiquitylation.

The five-letter string that represents the sorted events from the release of cargo by Pex5 is thus 'CEBDA'.