An antibody against a fluorescent protein is not there to see the fluorescence; it is there to detect the tagged protein on a blot, to pull it down, or to read it after the fluorophore has been destroyed by fixation and processing. That makes cross reactivity between the variants the first question, because most of these proteins are the same scaffold with a handful of mutations.
An anti-gfp antibody and an anti yfp antibody on the same scaffold
Yellow and cyan variants differ from the green parent by a few residues, so a polyclonal raised against green fluorescent protein usually recognises them all, and a monoclonal may or may not depending on where its epitope sits. That is convenient when one reagent has to serve several constructs and a problem when two tags have to be told apart in the same sample. Read the datasheet's cross reactivity panel rather than the name, and where discrimination matters choose clones validated against each variant separately.
An anti-mcherry antibody, an anti mcherry antibody and rfp antibody naming
The red proteins come from a different parent, so an antibody raised against the green family does not see them. Within the red set, mCherry, mRFP and their relatives share most of their sequence, which is why a reagent sold as an RFP antibody often detects mCherry and why the catalogue names are used loosely. When a construct will be detected for years, pin the clone rather than the name, record it with the construct, and check it against the exact variant your plasmid encodes rather than against the family.
An anti tdtomato antibody and an anti v5 antibody, and why the epitope matters
tdTomato is a tandem dimer, so it carries two copies of the epitope per molecule, which raises signal and can make quantification non-linear against a single-copy standard. V5 is a short peptide tag rather than a protein, so the antibody sees a defined sequence and the tag is small enough to leave function alone, at the cost of a weaker signal per molecule. The general rule follows from that: protein tags give signal, peptide tags give innocence, and the choice belongs with the construct design.
An anti luciferase antibody, a firefly luciferase antibody and a luciferase antibody generally
Luciferases are unrelated enzymes sharing a name, so specificity here is not a nicety: firefly luciferase is a sixty-one kilodalton protein, the small marine enzymes are around twenty, and an antibody against one does not see the other. That is why a reagent has to be matched to the enzyme in the construct. The usual reasons to blot for a luciferase rather than read its light are to check expression when the assay reads low, and to confirm that a fusion is intact rather than cleaved.
gaussia luciferase and what a secreted reporter changes
Gaussia luciferase is secreted, so the reporter accumulates in the medium and the same culture can be sampled repeatedly without lysis, which is what makes it useful for time courses. For a blot that means the protein is looked for in conditioned medium rather than in a lysate, concentrated if the expression is low, and read against a loading control that also comes from the medium. Its light output is flash rather than glow kinetics, which is a plate reader consideration rather than an antibody one.
A gfp elisa kit against a blot
A kit quantifies the tagged protein against a standard curve, which a blot does not do honestly, and it is the right tool when the number matters: expression across a transfection series, residual reporter in a preparation, or a comparison between vector doses. What it gives up is the molecular weight information that tells you the fusion is intact. Running both once on the same samples is worth the afternoon, because a kit reading high on a degraded fusion is a real and quiet failure.
A c-myc antibody and a myc antibody, tag against target
Two different reagents share this name. An antibody against the c-Myc protein detects an endogenous transcription factor at low abundance in the nucleus, and it is used in cancer biology. An antibody against the Myc tag detects a ten residue peptide derived from that protein and fused to a construct, and it is used for detection and purification. They are not interchangeable, and a datasheet distinguishes them by immunogen rather than by name, so the immunogen is the line to read.
Choosing between a tag and a direct antibody
Where a good antibody exists against the protein itself, use it: nothing is added to the construct and endogenous protein is measured alongside the transfected one. Tags earn their place when no antibody exists, when the same detection reagent has to serve many constructs, or when purification and detection should use the same handle. The cost is that the tag can change trafficking, folding and interaction, which is why a tagged construct is checked for function before conclusions rest on it.
Questions people ask about bfp antibody
Will an anti-GFP antibody detect YFP?
Usually with a polyclonal, since the variants share most of the scaffold, and unpredictably with a monoclonal. Where two variants must be told apart, use clones validated against each.
Why blot for a fluorescent protein at all?
To confirm the fusion is intact, to detect it after fixation and processing have destroyed fluorescence, and to pull it down.
Is a Myc antibody the same as an anti-Myc-tag antibody?
No. One detects the endogenous transcription factor, the other a short peptide tag from it. Read the immunogen, not the name.