Molecule of the Month: GFP-like Proteins
GFP-like proteins found in nature or engineered in the laboratory now span every color of the rainbow
Expanding the Palette
A Rainbow of Fluorescence
Exploring the Structure
Split GFP (PDB entry 4kf5)
Researchers have used these fluorescent proteins in many clever ways. For example, to study protein interactions, they can split GFP into two pieces and attach one piece to each protein. Then, if the two proteins get close to one another in the cell, the GFP will assemble and light up. PDB entry 4kf5 shows an example of a split GFP, in this case, used as a method to assist crystallization of proteins for structure determination. Two beta strand segments of GFP are fused to a protein of interest (in this case, sfCherry, colored red here), and a version of GFP is created that lacks these two strands (colored green). When the two engineered proteins are mixed together and interact with one another, the two portions of GFP assemble into a functionally fluorescent protein, with the cargo of sfCherry. To explore this engineered complex in more detail, click on the image for an interactive JSmol.
Topics for Further Discussion
- Structures for several proteins fused with GFP are available in the PDB archive, for instance, PDB entry 4anj has GFP fused with myosin.
- Be sure to look around the internet for micrograph images of cells with GFP-labeled proteins--for particularly beautiful images, try searching for "brainbow" or "fluoresence micrograph cytoskeleton"
June 2014, David Goodselldoi:10.2210/rcsb_pdb/mom_2014_6