Certain statements are made below regarding radio-receptor assay technique.
A. It is a competitive protein binding method.
B. It is a non-competitive protein binding method.
C. Radioligand is present in excess of unlabelled ligand.
D. Unlabelled ligand is present in excess of radioligand.
E. Activated charcoal incubation and further centrifugation lead to separation of free ligand in the charcoal pellet.
F. Activated charcoal incubation and further centrifugation lead to separation of bound ligand in the charcoal pellet.
Which one of the following options is the combination of all correct statements?

Correct option is C

The correct answer is: (3) A, D and E

Explanation:

In a radio-receptor assay, specific conditions and components are involved in determining the binding of radiolabeled ligands to their receptors. Let's analyze each statement:

• Statement A: It is a competitive protein binding method.
  Correct – The radio-receptor assay method is competitive because it involves competition between radiolabeled and unlabeled ligands for binding to the receptor.

• Statement B: It is a non-competitive protein binding method.
  Incorrect – This method is competitive and not non-competitive.

• Statement C: Radioligand is present in excess of unlabeled ligand.
  Incorrect – In radio-receptor assays, unlabeled ligands are typically present in excess, and the goal is to observe how radiolabeled ligand competes for receptor binding.

• Statement D: Unlabeled ligand is present in excess of radioligand.
  Correct – This is typically the case in radio-receptor assays where unlabeled ligands are used in excess to compete with the radiolabeled ligand for receptor binding.

• Statement E: Activated charcoal incubation and further centrifugation lead to separation of free ligand in the charcoal pellet.
  Correct – The charcoal method is used to separate bound and free ligands. After incubation, charcoal binds to the free ligand, and the bound ligand can be separated by centrifugation.

• Statement F: Activated charcoal incubation and further centrifugation lead to separation of bound ligand in the charcoal pellet.
  Incorrect – Charcoal binds to the free ligand, not the bound ligand.

Information Booster:

• Radio-receptor assay is a quantitative technique to study ligand-receptor interactions.

• It involves the competition between radiolabeled and unlabeled ligands to determine the affinity and concentration of the receptor.

• The process uses activated charcoal to separate free ligands from bound ligands.

• This method helps quantify the specific binding of a ligand to a receptor, which is essential in pharmacology and biochemistry.

• The method is widely used for characterizing receptor properties, such as affinity, specificity, and density.

• The assay can be used in drug development to understand how drugs interact with their target receptors.