Q.98 A green fluorescent protein (GFP) encoding gene is fused to a gene encoding specific protein for
expression in cells. What is the advantage of using GFP over staining cells with fluorescently
labeled antibodies that bind to the target protein?
(A) It bleaches less compared to fluorescent probes.
(B) It allows imaging at higher resolution than fluorescent probes.
(C) It provides more precise location of the protein than fluorescent probes.
(D) Its fusion allows tracking the location of the protein in living cells, while staining usually
requires fixation of cells.
GFP vs. Fluorescent Antibodies: Key Advantage in Live-Cell Imaging
Green Fluorescent Protein (GFP) fusion offers a powerful edge over traditional antibody staining for tracking proteins in cells. The correct answer is option (D), enabling real-time monitoring in living cells.
Correct Answer
(D) Its fusion allows tracking the location of the protein in living cells, while staining usually requires fixation of cells.
Why GFP Excels
GFP is genetically fused to the target protein and expressed inside cells, producing fluorescence naturally without external labels. This genetic encoding lets researchers observe protein dynamics like movement or localization in real time using live-cell microscopy.
Antibody staining, however, needs cell fixation and permeabilization to allow antibodies access, killing cells and halting processes.
For biotech students and researchers, this makes GFP vital for studying dynamic events like protein trafficking or host-pathogen interactions.
Option Breakdown
| Option | Explanation | Why Incorrect |
|---|---|---|
| (A) It bleaches less compared to fluorescent probes. | GFP can photobleach under prolonged excitation, similar to many organic dyes used in antibodies; no broad superiority here. | Not the primary or unique advantage. |
| (B) It allows imaging at higher resolution than fluorescent probes. | Resolution depends on microscope type (e.g., confocal), not the label; both GFP and antibody probes work similarly. | Resolution is equipment-limited, not label-specific. |
| (C) It provides more precise location of the protein than fluorescent probes. | Both methods offer comparable precision; antibodies bind epitopes directly, while GFP shows fusion site accurately. | Precision is equivalent in fixed samples. |
| (D) Its fusion allows tracking the location of the protein in living cells, while staining usually requires fixation of cells. | GFP enables non-invasive, live imaging without disrupting cells. | Correct: Captures the core benefit for dynamic studies. |
Applications in Molecular Biology
In bioinformatics and biotech labs, GFP tracks gene expression or protein interactions live, aiding tools like BLAST for sequence validation or CLUSTAL for fusion design. This suits exam prep on protein engineering or live imaging techniques.
