Question

Histamine is a chemical substance released in inflammatory and allergic responses. The histamine H1 receptor is a G protein-coupled receptor that activates phospholipase C in response to the binding of histamine. Complete the flowchart showing the process of histamine signal transduction from the H1 receptor. Place the items in the correct order:1. Calcium ions flow through the ligand-gated ion channel 2. Calcium ions activate a protein, leading to a cellular response 3. Calcium ion concentration increases in the cytosol. 4. IP 3 binds to a ligand-gated ion channel in the ER membrane 5. Enzyme cleaves PIP2, forming DAG and lP3

Answer 1

The procedure of histamine signal transduction from the H1 receptors occurs as per the sequence is given below:

a. The enzyme cleaves PIP2, producing IP3 and DAG.

b. IP3 combines with a ligand-gated ion channel in the endoplasmic reticulum membrane.

c. The flowing of calcium ions takes place through the ligand-gated ion channel.

d. The concentration of calcium ion enhances in the cytosol.

e. The activation of a protein is done by the calcium ions, resulting in a cellular response.