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- Table of Contents
CR2 / Complement receptor type 2 · Western blot design guide
Design a Western Blot for CR2
Real validated CR2 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-CR2 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Evidence assembled September 2026 · For research use; verify linked source records and product datasheet before use
CR2 Western Blot Experimental Design Guide
Expected bands, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before running
| Expected band | ~112.9 kDa | |
| Observed band | ~100 and 150 kDa | |
| Gel | 5–20% (catalog A01632-5) | |
| Positive control | Appendix (IHC candidate; verify WB) +3 more | |
| Negative control | Adipose tissue (IHC candidate; verify WB) |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Glycosylated + Cleaved | |
| Caveat | Modification-state controls | |
| Gene-set association | MSigDB Hallmark membership | |
| Isoform | 4 isoform(s) |
Section 1
Real Curated CR2 Western Blot Protocols
The A01632-5 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.
| Sample / lysate | mouse Raw264.7, mouse Ana-1 (catalog A01632-5) |
| Gel % | 5–20% (catalog A01632-5) |
| Load | 30 ug; reducing conditions (catalog A01632-5) |
| Transfer | a nitrocellulose membrane at 150 mA for 50-90 minutes (catalog A01632-5) |
| Membrane | nitrocellulose membrane (catalog A01632-5) |
| Blocking | 5% non-fat milk/TBS for 1.5 hour at RT (catalog A01632-5) |
| Primary antibody | A01632-5 · 0.5 μg/mL (catalog A01632-5) |
| Primary incubation | overnight at 4°C (catalog A01632-5) |
| Secondary antibody | goat anti-rabbit IgG-HRP, 1:5000 (catalog A01632-5) |
| Secondary incubation | 1.5 hour at RT (catalog A01632-5) |
| Wash | TBS-0.1%Tween 3 times with 5 minutes each (catalog A01632-5) |
| Detection | ECL (catalog A01632-5) |
Section 2
What Is the Expected CR2 Western Blot Band Size?
CR2 is predicted at 112.9 kDa, while antibody QC reports ~100 and ~150 kDa bands; the cause of their difference from prediction is not established.
| Bands near 100 and 150 kDa | Both were reported in antibody QC; their identities need controls. |
| Band near 113 kDa | Near the 112.9 kDa predicted precursor mass. |
| Broad band or smear | Heterogeneous N-linked glycosylation is possible but unproven as the cause. |
| Several discrete bands | Isoforms A, B, C and D exist, but distinct migration is unestablished. |
| Band below the precursor size | Signal-peptide removal may reduce mass; the size of the mature band is unknown. |
💡Expected CR2 appearanceCR2 has a predicted precursor mass of 112.9 kDa, while antibody QC reports bands near 100 and 150 kDa; use positive and negative controls to assess band identity.
| Predicted precursor mass | 112.9 kDa is the sequence-based reference, not an empirically established migration position. |
| N-linked glycosylation at Asn121, Asn127, Asn294, Asn372, Asn492, Asn623, Asn682 and Asn800 | May alter apparent size, but its contribution to the observed 100 and 150 kDa bands is unestablished. |
| Signal peptide at residues 1–20 | Cleavage yields a smaller mature chain; its apparent band size is not supplied. |
| Isoforms A, B, C and D | Could differ in size, but their individual masses and migration are not supplied. |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | Membrane CR2 may be poorly recovered during extraction. | Check membrane protein recovery and run a CR2-positive lysate. |
| Band higher than expected | N-linked glycosylation may affect migration, but the 150 kDa band has no established explanation. | Compare positive and negative controls and assess glycosylation with an appropriate enzyme control. |
| Band lower than expected | Signal-peptide cleavage may reduce mass, but it does not establish the 100 kDa band’s identity. | Compare positive and negative controls and confirm the antibody-recognized band. |
| Broad smear instead of sharp band | Heterogeneous N-linked glycosylation is possible. | Compare untreated and appropriately deglycosylated samples. |
| Multiple bands | CR2 has four isoforms, but their distinct migration is unestablished. | Compare bands across CR2-positive and CR2-negative controls. |
| Weak or no signal | Recovery of this membrane protein may be low. | Check membrane extraction and include a CR2-positive control. |
Experiment evidence
Western blot images showing CR2 band
A01632-5 · CR2
M01632 · CR2
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for CR2 Western blot
🧪HPA-IHC candidate guidance (verify in WB): For positive controls for CR2 in Western blot, you can use appendix tissue, which has high HPA expression.
Positive control: Appendix (IHC candidate; verify WB)
Negative control: Adipose tissue (IHC candidate; verify WB)
Loading controls: Run GAPDH, β-actin, and a total-protein stain alongside.
⚠️Feasibility: As a cell-membrane protein, CR2 may be easier to detect in a membrane-enriched lysate.
HPA tissue expression evidence for CR2
Comprehensive Human Protein Atlas IHC scoring per tissue. Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Higher expression tissues · candidate positive controls from IHC
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Appendix | lymphoid tissue | High | Protein (IHC) | HPA → |
| Lymph node | germinal center cells | High | Protein (IHC) | HPA → |
| Spleen | cells in white pulp | High | Protein (IHC) | HPA → |
| Tonsil | germinal center cells | High | Protein (IHC) | HPA → |
Lower expression tissues · IHC evidence, not confirmed WB-negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CR2 Western Blot Tips
Deeper troubleshooting and optimisation questions for CR2, answered from its protein features.
How should CR2 band migration be interpreted?
Band shift · Use the separately labelled calculated mass and catalog-observed evidence above. A sequence annotation does not establish an observed migration shift. Verify target identity with orthogonal controls.
Could CR2 isoforms produce different bands?
Isoforms · CR2 has isoforms A, B, C, and D. Relative to the canonical UniProt sequence, B lacks 499..524 and substitutes 525..556; C and D alter position 659; D also lacks 716..723. Consider these differences when selecting an antibody epitope and interpreting bands. The listed variants do not establish their apparent masses.
Which CR2 glycosylation sites should I consider?
PTM · UniProt lists N-linked sites at positions 121, 127, 294, 372, 492, 623, 682, 800, 823, 861, and 911. These are UniProt coordinates. Compare matched samples before and after N-glycan removal to assess whether glycosylation contributes to apparent mobility; the site list alone cannot explain a specific band.
Does this guide establish induction of CR2?
Induction · No general induction response is established by this guide. A pathway or gene-set association is not evidence of induction in a particular specimen. Verify the relevant treatment and control in a target-specific experiment.
How should transfer be checked for CR2?
Transfer · Standard workflow guidance: verify transfer efficiency for the intended target size before interpreting a weak signal. Use total-protein assessment and optimize transfer for the membrane, gel and apparatus; the labelled catalog values take precedence.
How should blocking be optimized?
Blocking · Standard workflow guidance: follow the A01632-5 datasheet where specified. Otherwise compare 5% milk or 5% BSA in TBST; for a phospho-specific assay start with BSA. Optimize background and specific signal with matched controls.
How should I quantify the two reported CR2 bands?
Quantitation · Measure the approximately 100 and 150 kDa bands separately under identical sample and blot conditions. Report which band was measured. The supplied features do not establish whether both bands represent CR2 or whether they should be combined into one abundance value.
How should I interpret CR2 bands near 100 and 150 kDa?
Interpretation · The reported bands are approximately 100 and 150 kDa, while the predicted mass is 112.9 kDa. CR2 has a signal peptide, N-linked glycosylation sites, and alternative isoforms. These features warrant investigation, but none assigns either band or establishes the size of a shift.
UniProt annotates a signal peptide at positions 1..20. Account for that segment when comparing the 112.9 kDa predicted mass with a mature CR2 species. Its presence does not establish which observed band represents mature CR2.
Yes. CR2 has 30 annotated disulfide bonds. Keep sample reduction conditions consistent when comparing lanes; differing conditions could complicate mobility comparisons. The disulfide annotations do not predict a particular band position.
Check whether the antibody epitope is present in the isoforms being studied, particularly across the annotated variable regions. Compare matched samples under consistent reduction and glycosylation treatment. CR2's four isoforms and 11 N-linked sites provide possibilities to test, not identities for unexpected bands.
UniProt annotates a signal peptide at positions 1..20. Account for that segment when comparing the 112.9 kDa predicted mass with a mature CR2 species. Its presence does not establish which observed band represents mature CR2.
Yes. CR2 has 30 annotated disulfide bonds. Keep sample reduction conditions consistent when comparing lanes; differing conditions could complicate mobility comparisons. The disulfide annotations do not predict a particular band position.
Check whether the antibody epitope is present in the isoforms being studied, particularly across the annotated variable regions. Compare matched samples under consistent reduction and glycosylation treatment. CR2's four isoforms and 11 N-linked sites provide possibilities to test, not identities for unexpected bands.
Boster reagents
CR2 Western Blot Antibodies
Catalog antibodies with Western blot application and product-specific WB images. Evaluate suitability with the reported sample, controls and experimental conditions.
Real WB data
Anti-CD21/CR2 Antibody Picoband®
Cat # A01632-5
Real WB data
Anti-CD21 CR2 Rabbit Monoclonal Antibody
Cat # M01632
Two the supplier anti-CR2 antibodies list human and mouse reactivity and have WB images. A01632-5 shows bands near 100 and 150 kDa in mouse Raw264.7 and Ana-1 lysates; M01632 shows CD21 expression in Raji lysate. These images document specific tested samples only.
Which to pick: Choose A01632-5 for a mouse lysate starting point: its image includes Raw264.7 and Ana-1 samples and detailed conditions. M01632 has a Raji lysate image, but its supplied caption gives no protocol details. Both list human and mouse reactivity.
Source: BosterBio CR2 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P20023.
- Human Protein Atlas. CR2 tissue expression.
- PMC3439536 — target-verified WB comparison
- PMC4133946 — target-verified WB comparison
- PMC3707406 — target-verified WB comparison