CD21 CRISPR/Cas9 KO Plasmid (h): sc-401352

Overview

CR2 encodes CD21 (complement receptor 2), a B cell and follicular dendritic cell surface glycoprotein that binds complement fragments such as C3d to modulate antigen capture and B cell activation thresholds. CD21 participates in B cell receptor co-receptor signaling with CD19 and CD81, integrating complement-dependent cues to tune MAPK and PI3K pathway outputs during germinal center responses and antibody maturation. It also serves as a receptor for Epstein–Barr virus, linking CR2 biology to studies of viral entry, latency, and B cell transformation. Altered CD21 expression or function has been investigated in contexts of immune dysregulation, including autoimmunity and B cell malignancy-associated microenvironmental signaling.

CD21 CRISPR/Cas9 KO Plasmid (h) is a pool of plasmids designed for targeted disruption of the CR2 gene in human cell lines. Each plasmid in the pool co-expresses a unique sgRNA, targeting a distinct site within the CR2 locus, alongside the Streptococcus pyogenes Cas9 nuclease, and encodes GFP to enable fluorescent identification and enrichment of successfully transfected cells. This multi-guide strategy increases the likelihood of inducing frameshifts or deletions that produce a functional knockout, offering a more robust alternative to single-guide approaches. DSBs induced at multiple sites are resolved through non-homologous end joining (NHEJ) or, when used with the included HDR donor template, homology-directed repair (HDR) at a defined target site within the locus.

When used in conjunction with the RFP-expressing HDR donor, GFP and RFP fluorescence can be used together to distinguish transfected from edited cell populations, streamlining flow cytometry-based sorting and clone selection workflows.

Homology-Directed Repair (HDR) Donor — Puromycin Cassette with RFP Reporter

For applications requiring confirmed, selectable knockout clones, CD21 HDR Plasmid (h) includes an HDR donor construct containing a puromycin resistance cassette (PuroR) and a red fluorescent protein (RFP) reporter, flanked by homology arms specific to a defined CR2 target site.
When co-transfected with CD21 CRISPR/Cas9 KO Plasmid (h):

• The PuroR-RFP cassette integrates at the Cas9 cut site via HDR, disrupting the CR2 open reading frame.
• RFP fluorescence provides an immediate visual indicator of successful integration, enabling fluorescence-based identification or sorting of edited cells prior to or alongside puromycin selection.
• Successfully edited cells are confirmed through puromycin resistance, substantially reducing clone screening burden.
• This selection strategy is ideal for generating stable, clonal KO cell lines for downstream functional studies, drug screening, or model development.

Cre-lox Cassette Removal System

The HDR donor construct features loxP sites flanking the PuroR-RFP selection cassette to allow clean marker removal following clone confirmation. Transient expression of Cre recombinase via the included Cre Vector: sc-418923 excises the cassette, leaving a minimal residual loxP site within the CR2 locus and eliminating potential confounding effects on downstream assays.
This two-step approach:

• Minimizes disruption to local chromatin architecture and neighboring regulatory elements
• Restores a near-native genomic context at the edited locus
• Enables reuse of the puromycin selection strategy in the same cell line for additional edits

Key Features

• gRNA targeting CR2 exon(s) critical for CD21 function
• Co-expression of SpCas9 and sgRNA from a single plasmid for simplified delivery
• HDR donor with puromycin resistance for positive clone selection
• loxP-flanked PuroR cassette with Cre recombinase vector for seamless marker removal
• Supplied ready to use for delivery by transfection

For Research Use Only. Not Intended for Diagnostic or Therapeutic Use.