Tunable tag for protein imaging

Tunable tag for protein imaging

Since the 1990s, molecular biologists have tagged biomolecules with proteins that fluoresce when exposed to light to observe and decipher fundamental cellular processes.

Although green fluorescent protein (GFP), a well-known tracer, has long been used for protein imaging, most GFP-like proteins are too large, slow to fluoresce, and unstable for many applications.

Researchers in the journal PNAS describe a protein tag dubbed Yellow Fluorescence-Activating and absorption-Shifting Tag (Y-FAST), which is much smaller in size than GFP and fluoresces instantaneously upon activation by a cell-permeant and nontoxic ligand.

The authors engineered Y-FAST from photoactive yellow protein using directed evolution, a laboratory technique that mimics the process of natural selection to produce proteins with specific characteristics.

The engineered traits allow Y-FAST to label targets with a high degree of selectivity and in a reversible manner, thus providing a fluorescence on/off switch.

According to the authors, Y-FAST compares favorably to other fluorescent proteins in terms of brightness and stability and is less likely to perturb the normal function of its binding targets.