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Short answer
Precision Plus Protein standards are Bio-Rad’s family of molecular weight markers for gels and blots. Each variant is a mixture of ten recombinant proteins spanning 10 to 250 kD, sold in three forms: Dual Color (eight blue bands plus two pink reference bands), All Blue (ten blue-stained bands) and Unstained (ten Strep-tagged proteins). They differ in reference bands, loading volume by detection method and storage.
Definition and scope
A protein ladder is a set of proteins of known size run in a lane beside your samples, so the bands in the sample lanes can be read against it. In the Precision Plus family the manufacturer calls these products protein standards. All three variants contain ten recombinant proteins in the 10-250 kD range, so the choice between them is about how the bands are visualised and referenced, not about coverage. This page compares the three catalogue variants as the manufacturer describes them. For the general idea of protein markers, see the protein marker guide.
How the standards are used in practice
The manufacturer’s product pages specify a loading volume that depends on the detection method, which is the main practical difference between the variants.
- Dual Color (cat. 1610374): 10 µl for electrophoresis and 7 µl for blotting.
- All Blue (cat. 1610373): on mini gels, 10 µl for Coomassie staining, or 5 µl at a 1:10 dilution for fluorescent blot detection.
- Unstained (cat. 1610363): on mini gels, 10 µl for Coomassie, 10 µl for Stain-free, 1-3 µl for silver stain, 1-3 µl for SYPRO Ruby, and 1-10 µl for blot development.
The Dual Color standard is supplied in a loading buffer of 30% (w/v) glycerol, 2% SDS, 62.5 mM Tris pH 6.8, 50 mM DTT, 5 mM EDTA and 0.02% NaN3. The Unstained standard carries a Strep-tag on each of its ten proteins; the manufacturer states that this tag supports detection and molecular weight determination on western blots. After transfer, a marker lane is read alongside the target band, as described in how to interpret western blot results, and the gel run itself follows the usual SDS-PAGE workflow.
Variants compared
Figures below are the manufacturer’s published specifications for each catalogue number.
| Feature | Dual Color (1610374) | All Blue (1610373) | Unstained (1610363) |
|---|---|---|---|
| Composition | 10 recombinant proteins, 10-250 kD | 10 blue-stained recombinant proteins, 10-250 kD | 10 Strep-tagged recombinant proteins, 10-250 kD |
| Visible bands | 8 blue bands and 2 pink reference bands | Ten blue-stained bands | Not pre-stained; visualised by the chosen detection method |
| Reference bands | 2 (25 and 75 kD, pink) | 3 (25, 50 and 75 kD) | 3 (25, 50 and 75 kD) |
| Volume per lane | 10 µl electrophoresis; 7 µl blotting | 10 µl Coomassie; 5 µl at 1:10 for fluorescent blot detection | 1-10 µl depending on method (see list above) |
| Storage | 6 months at 4°C or -20°C until expiration date | 6 months at 4°C or 12 months at -20°C | -20°C; 24 months from manufacture |
| Pack size | 500 µl, 50 applications | 500 µl, 50 applications | 1 ml, 100 applications |
Where it matters for labs and supply decisions
Three differences in the table affect day-to-day lab handling. First, shelf life: the unstained format lists 24 months from manufacture at -20°C, while the two pre-stained formats list 6 to 12 months depending on temperature, so inventory and freezer-space planning differ by variant. Second, pack size: the unstained format is a 1 ml, 100-application pack against 500 µl and 50 applications for the others. Third, detection compatibility: the unstained format lists loading volumes for Coomassie, Stain-free, silver, SYPRO Ruby and blot development, whereas the pre-stained formats list fewer methods.
Common misunderstandings
- “Dual color” does not mean two sets of proteins. The Dual Color variant has ten proteins in total: eight blue bands and two pink bands, and the pink ones are the 25 and 75 kD references.
- The three variants do not share one loading volume. The listed volume depends on the variant and the detection method.
- Unstained does not mean undetectable on blots. The Strep-tag on each protein is what the manufacturer cites for detection and molecular weight determination on western blots.
- Storage is not the same across variants. The listed periods run from 6 months to 24 months, at different temperatures.
FAQ
What size range do Precision Plus Protein standards cover?
All three variants cover 10-250 kD with ten recombinant proteins.
Which variant has two reference bands?
Dual Color has two pink reference bands at 25 and 75 kD. All Blue and Unstained have three reference bands at 25, 50 and 75 kD.
How should the standards be stored?
Per the manufacturer: Dual Color for 6 months at 4°C or -20°C until the expiration date; All Blue for 6 months at 4°C or 12 months at -20°C; Unstained at -20°C for 24 months from manufacture.
Does the choice of standard change how I normalise a blot?
The marker lane gives size, not loading. Loading control and normalisation are a separate step, covered in western blot loading control normalization.
Sources
- Bio-Rad, Precision Plus Protein Dual Color Standards, cat. 1610374: product page (checked 2026-10-29).
- Bio-Rad, Precision Plus Protein All Blue Prestained Protein Standards, cat. 1610373: product page (checked 2026-10-29).
- Bio-Rad, Precision Plus Protein Unstained Protein Standards, cat. 1610363: product page (checked 2026-10-29).
