The Addgene Blog

Master plasmid fundamentals, CRISPR techniques, AAV serotype selection, and antibody applications. Written by scientists, for scientists.

Subscribe

Recent Posts

A heatmap showing on-target activity of SpCas9 variants against various targets, with WT-like cleavage indicated by green, no cleavage indicated by red, and intermediate cleavages in middle shades of yellow-green, yellow, and orange. The variants are ranked by activity and the targets are ranked by cleavability, with the result that the top-left corner (high activity, high cleavability) is green to show high cleavage, the bottom right corner (low activity, low cleavability) is red to show no cleavage, and an approximate staircase pattern divides the two colors. In each row, a miniaturized graph of off-target cleavage, normalized from 0 to 1, is shown. In general, these graphs show declining off-target cleavage among SpCas9 variants of lower activity. In each row, representing a particular target, one cell of the heatmap has been outlined in black to emphasize it as belonging to the target-matched variant. Each target-matched cell is the last in its row to show moderate yellow-green color rather than an orange color, indicating some on-target cleavage activity. Each target-matched variant has very low off-target cleavage.
A protein structure of ABE8e is shown, superimposed with cartoon representations of sgRNA and target DNA. Two TadA domains are highlighted. The catalytic domain contacts multiple bases of the non-target DNA strand, while the docking domain primarily contacts the other protein domains.
A photo of three people holding and touching a tray of small plants that are either bright green or dark purple.
A cartoon showing a simplified Cas9 and gRNA binding to DNA. The 3’ end of the gRNA is the scaffold sequence, bound by Cas9, where some DNA substitution is tolerated. The 20 bases on the 5’ end of the gRNA are the spacer sequence, which hybridizes with the genomic DNA, base pairing to the target strand.   The non-target strand of genomic DNA includes the same sequence as the spacer. The PAM consists of the three bases immediately 3’ of this spacer-matching sequence.  Within the gRNA spacer, the 3’ half is the seed sequence, where no DNA substitution is tolerated. The 5’ half, also the 5’ end of the entire gRNA, is the tail sequence, where DNA substitution is tolerated.
Blugene holding a plasmid and smiling.
A cartoon of four cells, all carrying a different plasmid. Each cell glows a different color, matching the plasmid it carries.

Sharing science just got easier... Subscribe to our blog