Small peptide tags (like ALFA) cause minimal disruption of proteins, but they typically lack fluorescence, which would enable knockin screening. Now, antigen-stabilizing fluorescent protein-fused nanobodies called ANGEL have been developed, which enable endogenous labeling guided by ALFA nanobodies. ANGEL fluorescence increased with genomic ALFA in-frame insertion, which enables fluorescence-activated cell sorting screening for knockins, endogenous protein labeling, imaging, degradation and interactome analysis in native cellular contexts.
- Zhe Wang
- Fang Hu
- Pingyong Xu