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IGF1 · Western blot design guide
Design a Western Blot for IGF1
Real validated IGF1 Western blot protocols, expected-band and isoform facts, troubleshooting for weak or shifted signal, and recommended anti-IGF1 WB antibodies. Everything you need to plan the experiment before you commit precious samples.
Last reviewed: May 2026 · Scientific review: Boster Bio technical team
IGF1 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 | ~21.8 kDa | |
| Gel | 12–15% | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your observed band may differ from the expected size.
| PTM | Cleaved | |
| Caveat | Propeptide cleavage variability | |
| Regulation | Myogenesis | |
| Isoform | 4 isoform(s) |
Section 1
Real Curated IGF1 Western Blot Protocols
Literature-validated Western blot parameters for IGF1 — gel percentage, transfer, blocking, antibody incubation and detection, extracted from published methods.
| Sample / lysate | human ovarian granulosa-like tumor cell line KGN |
| Membrane | PVDF membranes (IPVH08130, Millipore, USA) |
| Blocking | 5% non-fat milk |
| Primary antibody | 1:1000 (ab9572, Abcam, UK) |
| Primary incubation | overnight at 4 °C |
| Secondary antibody | 1:2000 |
| Detection | enhanced chemiluminescence detection system (Bio-Rad, USA) |
Section 2
What Is the Expected IGF1 Western Blot Band Size?
IGF-1's 21.8 kDa precursor is cleaved of its signal peptide and propeptide during secretion, so the mature circulating protein runs as a much smaller band than the full-length prediction.
| Single band near 21.8 kDa in whole-cell/intracellular lysate | represents the unprocessed 195-aa precursor before signal peptide and propeptide removal |
| Much smaller band well below 21.8 kDa in mature/secreted preparations | reflects loss of the 21-residue signal peptide and the 22-48 propeptide during maturation, leaving a markedly smaller mature chain |
| Little or no band in whole-cell lysate | IGF-1 is annotated as secreted, so little full-length or mature protein is retained intracellularly |
| Sharp single band with no smearing | no glycosylation sites are annotated, so no glycoform-driven mass heterogeneity is expected |
| Slight mobility shift between non-reduced and reduced samples | the three annotated intrachain disulfide bonds compact the mature domain, so non-reduced protein can migrate slightly faster than fully reduced protein |
| Multiple bands at different apparent masses | four annotated splice isoforms can yield precursors of differing length, appearing as extra bands depending on which isoform is expressed |
💡Expected IGF1 appearanceFull-length IGF-1 precursor runs near 21.8 kDa, but after signal-peptide and propeptide cleavage the secreted mature chain appears as a markedly smaller single band, with no glycosylation-driven smearing since no glyco sites are annotated.
| Predicted precursor mass (21.8 kDa, 195 aa) | sets the baseline size for the unprocessed full-length chain seen before maturation |
| Signal peptide (residues 1-21) | removed during secretion, reducing the apparent size of the mature band relative to the precursor |
| Propeptide (residues 22-48) | cleaved off during processing, further shrinking the mature chain well below the 21.8 kDa precursor mass |
| Three intrachain disulfide bonds (54-96, 66-109, 95-100) | compact the folded domain, so non-reduced samples can migrate slightly faster than fully reduced samples |
| Four splice isoforms | isoforms of differing precursor length may appear as additional bands at distinct apparent masses, described only qualitatively as relatively larger or smaller |
| No annotated glycosylation sites | band should run as a sharp single species rather than a smeared or shifted-higher glycoform pattern |
| Secreted subcellular location | mature band is best detected in conditioned media, serum, or plasma rather than whole-cell lysate |
| Situation | Likely cause | Next action |
|---|---|---|
| No band in lysate | IGF-1 is secreted, so little full-length or mature protein remains inside cells | probe conditioned media, serum, or plasma rather than whole-cell lysate |
| Band higher than expected | antibody is detecting the uncleaved precursor that still carries its signal peptide and/or propeptide | determine whether the sample reflects intracellular precursor versus secreted mature protein and interpret size accordingly |
| Band lower than expected | mature, processed IGF-1 lacking the signal peptide and propeptide runs much smaller than the 21.8 kDa full-length prediction | compare the band against the expected mature-form size rather than the precursor predicted mass |
| Multiple bands | four annotated splice isoforms can generate precursors of different lengths | confirm isoform expression by sequencing or RT-PCR, or use an antibody targeting a region common to all isoforms |
| Fragments below expected size | the small, disulfide-stabilized mature IGF-1 chain is susceptible to proteolytic degradation during handling | keep samples cold, add protease inhibitors, and minimize freeze-thaw cycles |
| Weak or no signal | secreted mature IGF-1 is a small, low-abundance peptide that can be under-loaded or run off low-percentage gels | use a high-percentage or gradient gel, a low-MWCO transfer membrane, and concentrated serum/media samples |
Experiment evidence
Western blot images showing IGF1 band
PA1374 · IGF1
← swipe / scroll for more images →
Real WB data behind the band-size expectations in this section.
Sample controls for IGF1 Western blot
🧪For positive controls for IGF1 in Western blot, you can use serum or conditioned medium from IGF1-secreting cells, since the supplied HPA tissue panel lists no tissue with detectable IGF1 protein and UniProt annotates IGF1 as Secreted rather than retained intracellularly.
Positive control: Serum or conditioned medium
Negative control: Adipose tissue
Loading controls: Run GAPDH and β-actin alongside a total-protein stain (stain-free gel, Ponceau S, or REVERT) as loading controls.
⚠️Feasibility: As a secreted protein with no detectable signal across the sampled HPA tissues, whole-cell lysates are a poor source for either control, so favor conditioned medium/serum for the positive and expect weak, hard-to-distinguish background in any tissue lysate used as negative.
HPA tissue expression evidence for IGF1
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.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
Undetected expression · recommended 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 → |
| Appendix | glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced IGF1 Western Blot Tips
Deeper troubleshooting and optimisation questions for IGF1, answered from its protein features.
Why does IGF1 run smaller than its predicted 21.8 kDa mass?
The 21.8 kDa mass reflects the preproprotein, including the 21-residue signal peptide (1-21) and 27-residue propeptide (22-48). Signal peptide removal during secretion and propeptide processing generate the much smaller mature, secreted form, so blots typically show a band well below the calculated mass rather than near 21.8 kDa.
How do the 4 IGF1 isoforms affect band pattern?
Alternative splicing produces four isoforms sharing the same mature IGF1 core but differing in C-terminal E-peptide extensions. Antibodies targeting the core detect all isoforms as a single band, while antibodies against variable C-terminal regions can reveal extra, isoform-specific bands of slightly higher apparent mass; confirm immunogen location before interpreting multiplicity.
Should IGF1 be run under reducing or non-reducing conditions?
IGF1 contains three disulfide bonds stabilizing a compact fold. Non-reducing conditions preserve this structure and can cause tighter, faster migration or aggregate-like smearing; reducing conditions (DTT or beta-mercaptoethanol) linearize the protein for consistent migration. Use reducing conditions for routine detection unless the antibody requires native, disulfide-intact conformation.
What drives changes in IGF1 expression for induction studies?
IGF1 is a secreted growth factor whose hepatic expression is classically induced by growth hormone signaling. For induction experiments, stimulate with growth hormone or serum and sample conditioned media or serum rather than cell lysate, since the mature protein is exported (Secreted) rather than retained intracellularly.
How to optimize blocking for IGF1 Western blots?
Because IGF1 is a small secreted factor often assayed from serum or conditioned media, use BSA-based blocking rather than milk, which contains endogenous IGF1 and can cause background or antibody depletion. A one-hour room-temperature block is generally sufficient given the protein's small size and lack of glycosylation.
What transfer method to use for IGF1 Western blot?
Because mature IGF1 is small after signal peptide and propeptide cleavage, use high-percentage (15-18%) gels with low-molecular-weight-optimized transfer: shorter transfer times, lower voltage, and 0.2 micron PVDF or nitrocellulose to prevent blow-through and retain the small protein on the membrane.
How to quantify secreted IGF1 accurately by Western blot?
With no glycosylation or listed modified residues, signal variability mainly stems from sample source (serum or conditioned media versus lysate) and reducing versus non-reducing conditions affecting migration. Standardize reducing conditions and sample type across replicates, and use a recombinant IGF1 standard curve for reliable quantitation.
What explains unexpected higher molecular weight IGF1 bands?
Higher-than-expected bands may represent unprocessed pro-IGF1 retaining its signal peptide or propeptide, isoform-specific E-peptide extensions from alternative splicing, or IGF1 retained in a ternary complex with IGFR1 or integrins if samples are not fully denatured before electrophoresis.
Boster reagents
Best IGF1 Western Blot Antibodies
BosterBio's IGF1 antibodies are among the best-performing WB antibodies on the market — well cited, thoroughly validated, and orthogonally cross-validated against negative tissues and complementary methods.
Real WB data
Anti-Insulin-like growth factor I IGF1 Antibody Picoband®
Cat # PA1374
For IGF-1 Western blots, Boster offers PA1374, an anti-IGF-1 antibody with a documented WB image showing detection of recombinant human IGF-1 protein (2.5ng) — a useful starting point for confirming assay sensitivity before running experimental samples.
Which to pick: Only one Boster IGF-1 antibody is catalogued here, PA1374. It has a published WB validation image (recombinant human IGF-1, 2.5ng), so it's the default choice; no alternative SKUs are available to compare reactivity or format against.
Source: BosterBio IGF1 gene-info card — filtered to Western-blot-capable antibodies; each card shows that product's actual WB validation figure.
References
- UniProt Consortium. UniProt entry P05019.
- Human Protein Atlas. IGF1 tissue expression.