Question

Describe the HSP-90 binding cycle?

A) ATP Binding, Conformational Change, Substrate Release
B) ADP Binding, Substrate Folding, ATP Hydrolysis
C) Co-chaperone Interaction, Nucleotide Exchange, Substrate Unfolding
D) Substrate Recognition, J Domain Binding, ATP Synthesis

Answer 1

The HSP-90 binding cycle involves substrate recognition, ATP binding and conformational change, co-chaperone interaction, nucleotide exchange, and substrate release, facilitating the correct folding of proteins.

Step-by-step explanation:

The HSP-90 binding cycle is an essential part of the molecular chaperone's function in assisting with protein folding and stabilization. It typically follows these stages:

1. Substrate Recognition - The molecular chaperone identifies and binds to the substrate protein that requires assistance in folding.
2. ATP Binding - ATP binds to HSP-90, triggering a conformational change that tightens its grip on the substrate protein.
3. Co-chaperone Interaction - The interaction with co-chaperones also assists in the proper folding of the substrate protein.
4. Nucleotide Exchange - After the folding process, ATP is hydrolyzed to ADP, leading to another conformational change.
5. Substrate Release - The properly folded protein is released from HSP-90, allowing it to function appropriately within the cell.

In summary, the cycle includes substrate recognition, ATP-driven conformational changes, interaction with co-chaperones, nucleotide exchange, and release of the folded protein.