user-defined upper limit for the number of target sequences returned
Alignment
region of similarity between target and query sequences
E-value
a BLAST statistic representing the significance of an alignment, values close to zero
indicate high sequence similarity with low probability of the similarity occurring by chance
Identities
the number of exact nucleotide or amino acid matches over the alignment, expressed as a fraction
and a percentage
Query Coverage
the length of the query sequence that matches the target sequence in the
alignment
Bit Score
a BLAST statistic measuring the quality of an alignment, higher values indicate a
more significant match
Span
the length of the alignment, including gaps
About Search by Sequence
Search by Sequence performs a nucleotide-nucleotide or protein-translated nucleotide BLAST search against
Addgene’s plasmid sequence database.
BLAST returns plasmids with similarity to the query sequence.
Results are sorted by E-value, a statistic from BLAST that describes the significance of a match.
Lower values are considered better matches.
FASTA headers and numbers at the beginning of each line will be removed.
The query should only contain DNA characters.
Tips for Success
Enter a distinct sequence that is an important, differentiating feature. For example, the coding region of
a gene, instead of the plasmid origin of replication.
Inspect the percent identity, query coverage, and alignment details to determine if a result match is satisfactory.
Visit the corresponding plasmid webpage to view additional details about a matching plasmid.
If no results are returned:
Try a different isoform or region of the desired sequence.
Choose a different BLAST database. Try the general “All Addgene Plasmids” (default selection),
instead of a specific database, such as “Plant Expression Plasmids”
Try selecting a different BLAST algorithm:
megablast: Designed for comparing sequences within the same, or closely related, species.
Default selection.
blastn: Designed for comparing sequences from different species. May return additional results,
if exact species match is not required.
blastn-short: Optimized for searching with shorter sequences (<= 30 nucleotides)
but can still be effective with slightly larger sequences.
tblastn: Designed for comparing protein sequences against a translated nucleotide sequence database.
Helpful for finding plasmids with codon-optimized sequences.
tblastn-fast: A faster version of tblastn that may return results more quickly, but is less sensitive
There may not be a match in our database.
You can adjust the Max Results setting on the results page from 25 to 500. If many sequences share the same top E-value,
only a truncated set of equally high-scoring matches will be shown. Set the Max Results to 500 to see more matches.
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Fully functional Cas enzymes will introduce a double-strand break (DSB) at a specific location based on a gRNA-defined target sequence. DSBs are preferentially repaired in the cell by non-homologous end joining (NHEJ), a mechanism which frequently causes insertions or deletions (indels) in the DNA. Indels often lead to frameshifts, creating loss of function alleles.
To introduce specific genomic changes, researchers use DNA repair templates with homology to the DNA flanking the DSB and a specific edit close to the gRNA PAM site. When a repair template is present, the cell may repair a DSB using homology-directed repair (HDR) instead of NHEJ. In most experimental systems, HDR occurs at a much lower efficiency than NHEJ.
Figure 1: Overview of NHEJ and HDR following cleavage by Cas9.
Browse, sort, or search the tables below for CRISPR plasmids designed to introduce a DSB. To learn more about NHEJ, HDR, and other CRISPR topics, read our CRISPR Guide.
Addgene has a large selection of CRISPR plasmids and resources. Find more CRISPR functions along with plasmids categorized by organism by visiting our CRISPR plasmids page. Find a comprehensive list of CRISPR resources by visiting our CRISPR reference page.
