SFR1 / Swi5-dependent recombination DNA repair protein 1 homolog · Western blot design guide

Design a Western Blot for SFR1

Source-linked SFR1 Western blot protocol options, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-SFR1 WB antibodies. Everything you need to plan the experiment before you commit precious samples.

Evidence assembled October 2026 · For research use; verify linked source records and product datasheet before use

Western blot protocol sheet for SFR1: expected band ~28.3 kDa, hero antibody A07683-1, catalog values and labelled standard workflow; separate PMC comparisons on the guide — Printable **SFR1** Western blot protocol sheet — expected band ~28.3 kDa, antibody A07683-1, controls and PMC citations. Open the full SFR1 WB guide →

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SFR1 Western Blot Experimental Design Guide

Expected bands, source-linked protocol options, controls and antibodies — the at-a-glance facts below, then the full design guide.

Must know before running

	Expected band	~28.3 kDa
	Observed band	22 kDa
	Gel	5–20% (catalog A07683-1)
	Negative control ⓘ	Suggested KO / knockdown lysate

Important caveats

Reasons your observed band may differ from the expected size.

	PTM	Phosphorylated + Acetylated
	Caveat	Modification-state controls
	Gene-set association	MSigDB C7 membership
	Isoform	3 isoform(s)

Section 1

Source-Linked SFR1 Western Blot Protocol Options

The A07683-1 protocol combines labelled catalog values with standard starting conditions. Published comparisons retain their own sample, reagent and detection scope.

Recommended Western blot protocol parameters
Sample / lysate	human A431, human U251, human Hacat, human Jurkat, rat liver, mouse brain, mouse liver (catalog A07683-1)
Gel %	5–20% (catalog A07683-1)
Load	30 ug; reducing conditions (catalog A07683-1)
Transfer	a nitrocellulose membrane at 150 mA for 50-90 minutes (catalog A07683-1)
Membrane	nitrocellulose membrane (catalog A07683-1)
Blocking	5% non-fat milk/TBS for 1.5 hour at RT (catalog A07683-1)
Primary antibody	A07683-1 · 0.5 μg/mL (catalog A07683-1)
Primary incubation	overnight at 4°C (catalog A07683-1)
Secondary antibody	goat anti-rabbit IgG-HRP, 1:5000 (catalog A07683-1)
Secondary incubation	1.5 hour at RT (catalog A07683-1)
Wash	TBS-0.1%Tween 3 times with 5 minutes each (catalog A07683-1)
Detection	ECL (catalog A07683-1)

Section 2

What Is the Expected SFR1 Western Blot Band Size?

SFR1 is predicted at 28.3 kDa, but antibody QC reports a 22 kDa band; the cause of the difference is not established.

What am I looking at on my blot?
Band near 22 kDa	Empirical SFR1 antibody signal; confirm identity with controls
Band near 28.3 kDa	Near the UniProt predicted mass; confirm identity with controls
Several bands at different positions	Isoforms 1, 2, and 3 are possible contributors, but their migration is unknown
Weak signal in a cytosolic fraction	SFR1 is annotated as nuclear

💡Expected SFR1 appearanceUniProt predicts 28.3 kDa, while antibody QC detects a band near 22 kDa in reducing whole-cell blots; the cause of the difference is unestablished, so confirm band identity with appropriate controls.

How each factor affects band size
UniProt predicted mass	28.3 kDa is the sequence-based estimate; the observed band is near 22 kDa
Isoform 1	Its individual mass and migration are not supplied
Isoform 2	Alternative splicing could change its size; its migration is not supplied
Isoform 3	Alternative splicing could change its size; its migration is not supplied

Why is my band missing or off?
Situation	Likely cause	Next action
No band in lysate	Nuclear SFR1 may be poorly recovered	Check extraction and compare with a nuclear-enriched fraction
Band higher than expected	An isoform is possible, but the band identity is unconfirmed	Compare with a second antibody or SFR1 depletion
Band lower than expected	The reported 22 kDa band lies below the 28.3 kDa prediction for an unestablished reason	Verify the band with SFR1 depletion or a second antibody
Multiple bands	Three splice isoforms are annotated, but distinct bands are not established	Check which bands respond to SFR1 depletion
Weak or no signal	Nuclear SFR1 may be underrepresented in the preparation	Check nuclear protein recovery and increase sample input if needed

Source: UniProt Q86XK3 Human Protein Atlas product datasheet (A07683-1)

Experiment evidence

Western blot images showing SFR1 band

A07683-1 · SFR1

← swipe / scroll for more images →

Real WB data behind the band-size expectations in this section.

Sample controls for SFR1 Western blot

🧪For positive controls for SFR1 in Western blot, you can use a separately validated SFR1-positive cell lysate, since HPA provides no positive sample candidate.

Positive control: No high/medium HPA tissue identified

Negative control: Suggested KO / knockdown lysate

Loading controls: Run GAPDH, β-actin, and a total-protein stain such as Ponceau alongside the samples.

⚠️Feasibility: HPA provides no tissue data, so tissue-based positive and negative controls cannot be selected from this evidence.

HPA tissue expression evidence for SFR1

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
No high/medium HPA tissues identified in the supplied evidence.

Lower expression tissues · IHC evidence, not confirmed WB-negative controls

Tissue	Cell type	Level	Evidence	Source
No lower-expression tissue rows available in the supplied evidence.

Section 3

Advanced SFR1 Western Blot Tips

Deeper troubleshooting and optimisation questions for SFR1, answered from its protein features.

How should SFR1 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 SFR1 isoforms produce different bands?

Isoforms · UniProt lists isoforms 1, 2, and 3. Isoform 3 lacks canonical residues 1–13; isoform 2 replaces canonical residues 1–4 with a different N-terminal sequence. These changes could affect antibody recognition or band position, but the supplied features do not predict their apparent masses. Check whether the antibody recognizes each isoform.

Which SFR1 modifications matter when interpreting bands?

PTM · UniProt annotates phosphoserine at position 61 and the entry ‘Phosphoserine N-acetylmethionine’ at position 64. Use UniProt numbering when comparing these sites with antibody or paper coordinates. The annotations do not establish that either modification causes a visible shift; verify any proposed phospho-dependent band experimentally.

Does this guide establish induction of SFR1?

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.

What transfer method to use for SFR1 Western blot?

Transfer · The canonical protein is predicted at 28.3 kDa, and the reported apparent band is 22 kDa. Choose and check transfer conditions for retention of proteins in that size range. The supplied UniProt features do not specify a membrane or transfer method.

How should blocking be optimized?

Blocking · Standard workflow guidance: follow the A07683-1 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 SFR1 bands be quantified across samples?

Quantitation · Quantify the same verified band across samples, using consistent fractionation and normalization. Because UniProt lists three isoforms and modified residues, establish what each measured band represents before combining intensities. The supplied features do not show that DNA damage increases SFR1 abundance.

Why might SFR1 appear at 22 kDa rather than 28.3 kDa?

Interpretation · The reported apparent band is 22 kDa, while the canonical sequence predicts 28.3 kDa. UniProt lists alternative sequences and modified residues, but these features alone do not establish the cause of the difference. Confirm band identity with an independent SFR1 antibody or a specific loss-of-signal control.

UniProt places SFR1 in the nucleus. Include a nuclear fraction or confirm that the whole-cell preparation recovers nuclear proteins. Compare equivalent sample fractions across conditions before interpreting differences in band intensity.

Check band identity before assigning an unexpected band to an isoform or modification. UniProt lists N-terminal changes in isoforms 2 and 3 and modified residues at positions 61 and 64, but does not link them to specific Western-blot bands. Compare antibodies with different epitopes or use a specific loss-of-signal control.

Boster reagents

SFR1 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

Western blot analysis of SFR1 using anti-SFR1 antibody (A07683-1). Electrophoresis was performed on a 5-20% SDS-PAGE gel at 70V (Stacking gel) / 90V (Resolving gel) for 2-3 hours. The sample well of each lane was loaded with 30 ug of sample under reducing conditions. Lane 1: human A431 whole cell lysates, Lane 2: human U251 whole cell lysates, Lane 3: human Hacat whole cell lysates, Lane 4: human Jurkat whole cell lysates, Lane 5: rat liver tissue lysates, Lane 6: mouse brain tissue lysates, Lane 7: mouse liver tissue lysates. After electrophoresis, proteins were transferred to a nitrocellulose membrane at 150 mA for 50-90 minutes. Blocked the membrane with 5% non-fat milk/TBS for 1.5 hour at RT. The membrane was incubated with rabbit anti-SFR1 antigen affinity purified polyclonal antibody (Catalog # A07683-1) at 0.5 μg/mL overnight at 4°C, then washed with TBS-0.1%Tween 3 times with 5 minutes each and probed with a goat anti-rabbit IgG-HRP secondary antibody at a dilution of 1:5000 for 1.5 hour at RT. The signal is developed using an Enhanced Chemiluminescent detection (ECL) kit (Catalog # EK1002) with Tanon 5200 system. A specific band was detected for SFR1 at approximately 22 kDa. The expected band size for SFR1 is at 28 kDa.

Anti-SFR1 Antibody Picoband®

Cat # A07683-1

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The catalog reports one anti-SFR1 antibody, A07683-1, with a Western blot image from human cell, rat liver, and mouse brain and liver lysates. The reported band is approximately 22 kDa, versus an expected 28 kDa; no independent validation is supplied.

Which to pick: A07683-1 is the only listed option. It reports human, mouse, and rat reactivity, with a WB image covering the named lysates. Consider the 22 kDa observed band and 28 kDa expected size when assessing your blot.

Source: BosterBio SFR1 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.

References

UniProt Consortium. UniProt entry Q86XK3.
Human Protein Atlas. SFR1 tissue expression.
PMC3706619 — target-verified WB comparison