How do you get an antibody specific to one phospho-site and not the rest?
Why phospho-specific antibodies fail
The antibody has to discriminate roughly 80 daltons on an otherwise identical sequence, then keep doing it against an entire proteome. Two failure modes dominate. The first is the pan-phospho antibody: it recognises a phosphate group in almost any context, so it lights up everywhere. The second is the peptide-only antibody: it works beautifully on the immunizing peptide and does nothing on the full-length protein.
Both are selection problems, not screening problems. By the time you are screening, the clones that cause them are already in the pool.
How we do it
You supply the synthetic phospho-peptide and its unmodified control. We pan the library and apply subtractive selection against the unmodified peptide and against an irrelevant phospho-peptide, so pan-phospho binders and non-discriminating clones are competed away during panning. pSer and pThr are both supported. You pay only for specificity-confirmed clones, and your sequences stay confidential.
Where the endpoint is a blot, a flow panel or an IHC section rather than an ELISA, we say so at scoping and screen for it — because a peptide number does not predict application performance. We have published the evidence for that: in a panel of PTM-specific rabbit antibodies, the tightest binder at 0.90 nM gave only a faint band on Western blot while 14 nM and 54 nM clones detected the full-length protein cleanly.
The published mechanism behind this service
Three peer-reviewed structural studies, co-authored with the University of Tokyo, document how antibodies made this way recognise post-translational modifications — and what determines whether they survive the jump from peptide to protein.
- Phospho-Akt (pSer473) — two clones, one at 335-fold selectivity over the unmodified peptide, one with no detectable binding to the unmodified peptide at all. Crystal structures deposited.
- Methylated lysine (MAP3K2 K260me3) — why the highest-affinity clone failed on Western blot, explained at atomic resolution.
- Sulfated tyrosine (CCR5) — an antibody that distinguishes not just sulfation but which tyrosine carries the sulfate.
- Phospho-specific clones with sequences
- Phospho versus non-phospho specificity data
- Western blot or flow validation where the application requires it
- Recombinant material — reproducible for the life of the assay rather than lot-limited
Beyond phosphorylation
The same selection logic applies to other post-translational modifications: methylation, acetylation, sulfation, and site-specific glycan or citrullination epitopes. If the modification can be presented on a synthetic peptide with a credible unmodified control, it can usually be selected against. Tell us the modification and the sequence context and we will give you a view on feasibility before you commit.
Have a phospho-site nothing commercial resolves?
Send the sequence and the assay it has to work in. A PhD scientist reads it and replies within two business days. No NDA needed to start.
Talk to a scientist →Frequently asked questions
Do I need to supply the peptide, or can you make it?
Either. Most sponsors supply the phospho-peptide and unmodified control because they have already validated the sequence choice. If you would rather we handle synthesis and conjugation, that is part of scope — and worth discussing, because carrier and C-terminal choices affect whether the resulting antibody can recognise full-length protein.
Can you make antibodies to doubly phosphorylated sites?
Often, and it is a common request for activation-loop epitopes. It needs the singly phosphorylated peptides as subtraction controls, so plan for three or four peptides rather than two.
Will the antibody work in IHC on fixed tissue?
Only if it is screened there. Fixation changes epitope presentation, so an antibody validated by Western blot does not automatically transfer. If IHC is the endpoint, that has to be in the screening cascade from the start.
How long does a phospho campaign take?
Immunization through validated recombinant IgG runs about four to six months for a typical target.
Are my target sequences confidential?
Yes. Sponsor sequences stay confidential, and the resulting clones and their sequences are returned to you with no downstream royalties in standard scope.