Which of the following statements are incorrect about receptor proteins?

Options

A. Majority of receptor proteins are embedded in the cell membranes.
B. The active site of receptor proteins opens on the inside region of the cell.
C. Chemical messengers are received at the binding sites of receptor proteins.
D. Shape of receptor doesn't change during attachment of messenger.

Answer

To determine which statements about receptor proteins are incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Majority of receptor proteins are embedded in the cell membrane."
- This statement is **correct**. Most receptor proteins are indeed embedded in the cell membrane, allowing them to interact with external signals.

2. **Statement 2**: "The active site of receptor protein opens on the inside region of the cell."
- This statement is **incorrect**. The active site of receptor proteins typically opens to the outside of the cell membrane, allowing them to bind to external chemical messengers.

3. **Statement 3**: "Chemical messengers are received at the binding site of receptor proteins."
- This statement is **correct**. Receptor proteins have specific binding sites where chemical messengers (like hormones or neurotransmitters) attach, initiating a response in the cell.

4. **Statement 4**: "Shape of receptor doesn't change during attachment of messenger."
- This statement is **incorrect**. When a chemical messenger binds to a receptor, the shape of the receptor often changes to accommodate the messenger. This change is crucial for the transmission of the signal into the cell.

### Conclusion:
The incorrect statements about receptor proteins are:
- **Statement 2**: "The active site of receptor protein opens on the inside region of the cell."
- **Statement 4**: "Shape of receptor doesn't change during attachment of messenger."

### Final Answer:
The incorrect statements are **2 and 4**.

---