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Table 1 Current characterization of Type II, V and VI effectors

From: Class 2 CRISPR/Cas: an expanding biotechnology toolbox for and beyond genome editing

Effectora Cas9 Cas12a Cas13a Cas13b Cas13d
Subtype II-A V-A VI-A VI-B VI-D
Target dsDNA dsDNA ssRNA ssRNA ssRNA
Nuclease domainb RuvC-NTS, HNH-TS RuvC-NTS, TS Nuc 2 HEPN 2 HEPN 2 HEPN
Pre-crRNA processing RNase III WED III Helical 1 or HEPN2 ? ?
tracrRNA Yes No No No No
Cut nature Staggered, 5′ 1- or 3-nt overhangs Staggered, 5 nt overhangs collateral activity-ssDNA Collateral activity-ssRNA Collateral activity-ssRNA Collateral activity-ssRNA
PAM/PFSc 3′G-rich PAM 5′T-rich PAM 3′ PFS: H 5′PFS: D;3′ PFS:NAN or NNA No?
Median size 1228 aa 1268 aa 1228 aa 1128 aa 928 aa
  1. a Characterized and validated types are included
  2. b TS and NTS indicate domain that cleaves target strand (TS) or non-target strand (NTS)
  3. c D: A, G, or U; H: A, C, or U; N: A, C, G, or T (or U)