Insulin receptors are

Options

A. G - protein
B. Cytoplasmic protein
C. Membrane protein
D. Trimeric protein

Answer

**Step-by-Step Solution:**

1. **Understanding Insulin**: Insulin is a peptide hormone produced by the pancreas. It plays a critical role in regulating blood sugar levels in the body.

2. **Function of Insulin**: The primary function of insulin is to lower blood glucose levels. It facilitates the uptake of glucose by cells, particularly in the liver, muscles, and adipose tissue, and promotes the conversion of glucose to glycogen for storage.

3. **Insulin Receptors**: Insulin receptors are specific proteins located on the cell membranes of target tissues. These receptors bind to insulin, allowing the hormone to exert its effects on glucose metabolism.

4. **Type of Insulin Receptors**: The question asks what type of proteins insulin receptors are. Insulin receptors are classified as membrane proteins because they are embedded in the cell membrane and play a crucial role in the signaling pathway initiated by insulin binding.

5. **Conclusion**: Therefore, the correct answer to the question "Insulin receptors are" is that they are **membrane proteins**.

---