Exploration of Digestive Diseases

Table 2. Fundamental classification of CRISPR types.

Class	Effector complexity	Type	Representative effector	Target	Key characteristics
Class 1	Multi-subunit complex	I	Cas3	DNA	Multiprotein complex, separate cleavage unit
		III	Cas10	RNA/DNA	Targets RNA, induces a broad immune response
		IV	Csf		Incomplete system, diverse functions
Class 2	Single effector protein	II	Cas9	DNA	Most widely used, requires tracrRNA
		V	Cas12	DNA	No tracrRNA needed, cis-cleavage activity
		VI	Cas13	RNA	Targets RNA, trans-cleavage activity

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CRISPR: clustered regularly interspaced short palindromic repeats.

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Author contributions

MZ: Writing—original draft. QS: Visualization. QZ: Writing—review & editing. XY: Conceptualization, Writing—original draft, Writing—review & editing, Supervision. All authors have read and agreed to the published version of the manuscript.

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