Which of the following statements about allosteric proteins is/are true?

• A. They are sensitive to environmental conditions.
• B. They are acted on by inhibitors.
• C. They exist in active and inactive conformations.
• D. None of the first three listed responses is correct.
• E. All of the first three listed responses are correct.

Answer: (E)

Verified step by step guidance

1. Understand that allosteric proteins are proteins that can change their conformation and activity in response to the binding of an effector molecule at a site other than the active site.
2. Recognize that allosteric proteins are sensitive to environmental conditions such as pH, temperature, and the presence of specific ions or molecules, which can affect their conformation and activity.
3. Identify that allosteric proteins can be regulated by inhibitors, which bind to the allosteric site and stabilize the inactive conformation, reducing the protein's activity.
4. Acknowledge that allosteric proteins can exist in both active and inactive conformations, allowing them to switch between these states in response to effector binding.
5. Conclude that all of the first three statements about allosteric proteins are true, as they describe the fundamental characteristics and regulatory mechanisms of these proteins.