​In vivo interaction between FLAG-tagged protein P and chaperone H was examined by co-immunoprecipitation (co-IP). Co-chaperone A was included, and the co-IP was performed in the presence or absence of cycloheximide (CHX). The results of the co-IP experiments are shown below.

​Based on the data, which of the following interpretations from these experiments is INCORRECT?​

Correct option is C

Let's analyze the Western blot results and the co-IP findings to determine which interpretation is incorrect.

1. Protein P interacts with chaperone H and co-chaperone A (Correct).

   • The co-IP results show bands for both chaperone H and co-chaperone A when FLAG-P is present, indicating that protein P interacts with both chaperones.

2. Chaperone H interacts only with newly synthesized protein P (Correct).

   • When CHX (cycloheximide) is added, which inhibits protein synthesis, the interaction between chaperone H and protein P is significantly reduced.
   • This suggests that chaperone H primarily interacts with newly synthesized protein P.

3. Interaction between co-chaperone A and protein P is independent of chaperone H (Incorrect).

   • The co-IP results indicate that co-chaperone A interacts with protein P only when chaperone H is also present.
   • This suggests that co-chaperone A requires chaperone H for its interaction with protein P, meaning that the interaction is dependent on chaperone H.

4. Interaction between chaperone H and protein P is independent of co-chaperone A (Correct).

   • The interaction between chaperone H and protein P occurs even in the absence of co-chaperone A, as shown in the co-IP bands where chaperone H is present regardless of co-chaperone A.
   • This means the interaction is independent of co-chaperone A.

Thus, the incorrect statement is Option 3, as co-chaperone A's interaction with protein P depends on chaperone H.

Information Booster

1. Cycloheximide (CHX) inhibits new protein synthesis, helping determine if chaperone binding is dependent on newly synthesized proteins.
2. Chaperone proteins assist in protein folding, stability, and complex formation.
3. Co-chaperones often require the presence of primary chaperones for interaction with target proteins.
4. Co-immunoprecipitation (co-IP) is used to study protein-protein interactions under different conditions.
5. If an interaction disappears with CHX treatment, it suggests that the protein binds to newly synthesized substrates.
6. If an interaction remains after CHX treatment, it suggests a stable interaction with mature proteins.