Table 3. Summary of the molecular and functional characteristics of programmable transposon systems.

System	CASTs (Type I–F)	CASTs (Type V–K)	TATSI (mPing-Cas9)	TPRT	STITCHR
Organism	Vibrionaceae[14,62]	Cyanobacteria[15,62]	Rice[13]	Bombyx mori [16]	Taeniopygia guttata [63]
Targeting strategy	RNA-guided[14,62]	RNA-guided[15,62]	RNA-guided[13]	RNA-guided[16]	RNA-guided[63]
Transposition mechanism	Cut-and-paste[14,62]	Cut-and-paste[15,62]	Cut-and-paste[13]	Cut-and-paste[16]	Cut-and-paste[63]
Targeting effector	Cas8–Cas5, Cas6, Cas7, and crRNA[14,62]	Cas12k, tracrRNA, and crRNA (sgRNA)[15,62]	Cas9, dCas9[13]	Cas9, dCas9[16]	Cas9, dCas9[63]
PAM	CC[14,62]	GT[15,62]	NGG[13]	NGG[16]	NGG
Transposase	TnsA and TnsB[14,62]	TnsB[15,62]	mPing[13]	R2 retrotransposon[16]	R2 retrotransposon[63]
Integration efficiency	100% in E. coli BL21(DE3); 1% in HEK293T cells[57,62,64]	95% in E. coli BL21(DE3); < 1% in HEK293T cells[58,62,65]	8.3% in Arabidopsis for 8.6-kb insert; 9.8% in soybean 9.8% for 1.5-kb insert[13]	< 300 bp in vitro[16]; 80% in human cells for 1.3-kb insert[66]	6%–12% in HEK293T cells for 1-bp to 12.7-kb insert[63]
Highlight	Highly specific targeting with complex effector composition	Compact yet sophisticated targeting effector composition	Insertion into specific target precisely	R2 can be retargeted with CRISPR/Cas9 and inserts small DNA fragments at the cleavage site in vitro	R2 can be retargeted with CRISPR/Cas9 and adds a single base to 12.7 kb DNA fragments at the cleavage site in vivo