Question

In studying receptor-ligand interactions, the researcher wanted to narrow down the exact region of binding between the receptor and the ligand. Amino acids 24 – 29 on the receptor were believed to be involved in ligand binding. So the researcher performed mutations in these amino acids and assayed the effect of these mutations by performing binding assays. Mutation amino acid 24​​​   Receptor-Ligand binding. No

​ If the amino acid 24 was mutated from a glycine to an arginine, and the binding assay results were negative, what would you conclude from these results about the role of this amino acid in binding to the ligand? (1 point)

Explain in detail and also suggest other amino acid changes that would help understand these results further.

Answer 1

Role of amino acid 24 in binding to the ligand:

A mutation in amino acid 24 disrupts receptor-ligand binding. Because mutation in amino acid 24 shows no receptor-ligand binding.

If we conclude the results in a hypothetical manner then we can suggest the results below (this is the hypothetical result because it is created on the basis of assumption):

Mutations                              Receptor-Ligand binding

Amino acid 24                                  No

Amino acid 25                                 Yes

Amino acid 26                                  No

Amino acid 27                                  Yes

Amino acid 28                                   No

Amino acid 29                                    Yes

Amino acids 24 and 25                       Yes

Amino acids 26 and 28 are directly involved in receptor-ligand binding. When amino acid 24 and amino acid 25 both are mutated, the ligand binds to the receptor. It can be suggested that a mutation in both amino acid 24 and amino acid 25 prevents the mutated amino acid 24 from disrupting the receptor ligand-bond.