What technique was used to characterize ASBT protein expression?

• A. RT-qPCR
• B. ELISA
• C. Immunohistochemistry
• D. Mass spectrometry

Answer: (C)

Immunohistochemistry is used to characterize where a protein is expressed within tissue because it combines a specific antibody for the target protein with a visible label on fixed tissue sections. For ASBT, this means the antibody binds to the transporter on the intestinal epithelium and, with a chromogenic or fluorescent signal, you can see exactly where ASBT sits—often at the apical brush-border membrane of enterocytes. This preserved tissue context lets you distinguish expression on the cell surface, within particular cell layers, or in specific regions of the gut.

Other methods assess different aspects: RT-qPCR measures mRNA levels and doesn’t provide protein localization; ELISA detects protein quantity in fluid or lysates but loses spatial information within the tissue; mass spectrometry can identify and quantify proteins but typically requires tissue homogenates and likewise lacks precise cellular localization unless paired with imaging approaches.