Question

p-gp (p-glycoprotein) is highly expressed on the

• A. Lungs
• B. Pancrea
• C. Superficial columnar epithelial cells of ileum and colon
• D. Heart

Answer 1

The Correct Option is C

The question asks about the locations where the protein P-glycoprotein (p-gp) is highly expressed. Let us understand the role of P-glycoprotein and identify the correct option based on its localization.

P-glycoprotein is a type of protein that acts as a drug efflux pump, removing toxins and drugs from cells. It is a member of the ATP-binding cassette (ABC) transporter family. Its function is crucial for the absorption, distribution, and excretion of various pharmaceuticals and endogenous compounds.

P-gp is most commonly expressed in tissues with excretory functions, such as:

• The apical membrane of superficial columnar epithelial cells lining the intestine (ileum and colon) - where it serves to reduce absorption of xenobiotics and regulate drug transport.
• The liver - contributing to biliary excretion.
• The kidneys - facilitating renal secretion.
• The blood-brain barrier - restricting drug entry into the central nervous system.

Considering these primary sites of expression, the most relevant option from the choices given is:

Superficial columnar epithelial cells of ileum and colon

Reasons for ruling out other options:

• Lungs: Although P-gp is present, its expression is not typically high compared to intestinal and other excretory tissues.
• Pancreas: Not a major site of P-gp expression.
• Heart: While it may be present in the heart, the levels are not as significant as in the ileum and colon.

Thus, the expression pattern aligns with the key role of P-glycoprotein in drug transport and metabolism, especially within the intestinal tract.