Table 1. Types and characteristics of cytidine deaminases in CBEs.

Cytidine deaminases	CBEnames	Engineering sites	Features	Target C preference	Reference
rAPOBEC1	BE3	WT	Canonical CBE architecture	5’-TC	Komor et al. 2016
	YE1-BE3 EE-BE3 YE2-BE3 YEE-BE3	W90Y, R126E R126E R132E W90Y, R132E W90Y, R126E, R132E	Showed constricted editing windows and reduced bystander editing compared to BE3	5’-TC	Kim et al. 2017
	SECURE	R33A, K34A	Reduced off-target RNA editing compared with BE3	5’-TC	Grunewald et al. 2019a
hAID	CRISPR-X	WT	Broad mutagenesis, increase in C-to-non-T edits relative to BE3	None	Hess et al. 2016,
	TAM	WT	Broad mutagenesis and C-to-non-T edits relative to BE3	None	Ma et al. 2016
PmCDA1	Target-AID	WT	Exhibits altered editing windows relative to N-terminal deaminase fusion relative to BE3	None	Nishida et al. 2016
hAPOBEC3A	eA3A-BE3	N57G	Reduced bystander editing and reduced off-target RNA-editing activity relative to BE3	5’-TC	Gehrke et al. 2018
	hA3A-BE3-Y130F hA3A-BE3-Y132D	Y130F Y132D	Narrower editing windows and reduced bystander editing	5’-TC	Wang et al. 2018
	hA3A-BE3-Y130F/Y132D	Y130F, Y132D	Narrowed editing windows
	BEACON1 BEACON2	W98Y, Y132D W98Y, W104A, Y130F	Narrowed editing window and induce low levels of indels	5’-TC	Wang et al. 2020
hAPOBEC3G	hA3G-BE	C-terminal catalytic domain of hA3G	Preferentially at 5’-CC-3’ motifs	5’-CC	Liu et al. 2020
mAPOBEC3	tBE	N-terminal catalytic domain of mA3	Eliminated OT mutations	5’-TC	Wang et al. 2021
Sdd3	/	WT	Expanded sequence context preference and lower off-target activities	5’-GC or 5’-AC	Huang et al. 2023
Sdd6	/	WT	Showed no strong sequence context preference and nearly no off-target editing activity.	None
Sdd7	/	WT	Showed no strong sequence context preference.	None