# DBT JRF 2020 — Question 90

Exam: DBT JRF 2020 · Section: B · Topic: Biochemistry · Difficulty: Medium

## Question

The location of a proteins in cells can be studied using

## Options

- **A.** X-ray crystallography
- **B.** NMR spectroscopy
- **C.** western blotting
- **D.** fluorescent microscopy

## Answer

Option D

## Explanation

Protein localisation within cells is determined by fluorescence microscopy techniques: (1) Immunofluorescence (IF) — fixed and permeabilised cells are incubated with primary antibody (anti-target protein) + fluorescently labelled secondary antibody; confocal/epifluorescence microscopy reveals subcellular location. (2) Live cell imaging with GFP (Green Fluorescent Protein) fusions — target protein genetically fused to GFP expressed in live cells; real-time location and trafficking visualised. (3) Super-resolution microscopy (STORM, PALM) — nanometre-scale resolution. Western blotting detects protein size/abundance in cell lysates — no spatial information. NMR and X-ray crystallography give atomic-level structural information, not in-cell location. Flow cytometry provides population-level surface marker data, not subcellular localisation.

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