Fig. 1
From: Class 2 CRISPR/Cas: an expanding biotechnology toolbox for and beyond genome editing
The genomic organization of generalized CRISPR/Cas loci in Class 1, Type II and Class 2 systems, illustrated according to Ref. [8, 120, 121]. The organization contains CRISPR-Cas loci and domain architectures of the effector proteins. Compared to Class 2 systems, Type II Cas9 systems need tracrRNA. Except for Type VI-B, Type II, VA and VIA all have their own CRISPR/Cas genes. For subtype VI-B, the activity of the effector protein Cas13b could be repressed by Csx27 protein and enhanced by Csx28