Finding out where specific RNA molecules are located in a cell just got a whole lot easier. Green fluorescent protein (GFP), makes protein localization in living cells, or even in whole animals, as simple as cloning a gene. But until now, there wasn’t an equivalent for RNA.
The number of noncoding RNA types known to biologists (such as transfer-, small nucleolar-, and microRNAs) has increased in recent years, and many of them have “completely mysterious” functions, says Samie Jaffrey at Weill Medical College, Cornell University. So he devised a way of directly labeling RNA with a fluorescent tag.
Jaffrey designed synthetic versions of the fluorescent moiety of GFP, called HBI, which is much smaller than the complete protein. Then, using a kind of in vitro evolution, he selected for RNA molecules that could bind the GFP-like fluorophores with high affinity and cause the complex to fluoresce when illuminated. A...
|Comparing Methods:||MACROMOLECULE||SIZE||PHOTO-BLEACHING||QUANTUM YIELD||MATERIAL REQUIRED|
|GFP||protein||238 amino acids||yes||0.79||expressed gene|
|Spinach||RNA||80 nucleotides||no||0.72||expressed gene + synthetic fluorophore in culture medium|