Table 1.

PL enzymes commonly used for PPI studies

Enzyme	Origin	Size (kDa)	Optimal temp (°C)	Labeling time	Labeling radius (nm)	Substrates and cytotoxicity	Model organisms
APEX	Pea	28	37	1 min	<20	Biotin–phenol + H2O2 (toxic)	Mammalian cells, flies
APEX2	Soybean						Mammalian cells, bacteria, Chlamydia, yeast
Split-APEX2						Biotin–phenol + H2O2 (toxic) + heme	Mammalian cells, yeast
HRP	Horseradish	44	37	≤1 min	200–300	Biotin–phenol + H2O2 (toxic)	Human and chicken cells
Split-HRP						Biotin–phenol + H2O2 (toxic) + heme	Mammalian, yeast cells
BioID	E. coli	35	37	18–24 h	∼10	Biotin (nontoxic)	Mammalian, plant cells, yeast
BioID2	A. aeolicus	25		18 h			Mammalian, plant cells
Split-BioID							Mammalian, plant cells
BASU	B. subtilis			1 min			Mammalian, plant cells
AirID	E. coli	37	26	3–24 h			Mammalian cells and wheat cell–free system
miniTurboID		28	25	≤10 min			Mammalian, plant cells, yeast, flies, and worms
TurboID
Split-TurboID		35		1 h			Mammalian cells