Choosing A Plasmid Backbone
When choosing what plasmid backbone to use, you have many elements to consider. Here is a guide to Addgene's empty vector backbones. For the most part, we will assume that you want to express a gene; however, we have a section at the end for if you are studying a different genetic element or want to express shRNA.
If you want to drive expression of your favorite gene, you will need a plasmid with a promoter that will be functional in your host organism.
|Host||Relevant Promoters||Representative Empty Backbones|
|Mammalian||CMV, SV40, EF1a, CAG|
|Bacteria||Lac, T7, araBAD||
|Yeast||GAL4, PGK, ADH1, ADE2, TRP1|
|Worm||unc-54, variety of worm gene promoters|
|Insect / Baculovirus||Polyhedrin|
|Xenopus||SP6 for transcription and injection|
Epitope Tag or Fusion Protein
Tags and fusion proteins are excellent tools for further understanding the function of your favorite gene. For example, fusing your protein to an epitope tag, such as Flag or HA, will allow you to easily identify your protein using an antibody against that epitope. This could allow you to conduct western blots or immunoprecipitations of your favorite gene even if you do not have an antibody against it. Another common scenario is fusing your protein to another protein, such as GFP, which allows you to visualize the cellular localization of your protein.
Just remember that when you are designing your plasmid you should keep your gene "in frame" with the fusion protein. This means that the final product should be translated as a single string of amino acids that preserves the sequence of your gene and of the fusion protein.
|Tag or Fusion Protein||Common uses||Representative Empty Backbones|
|Other Fluorescent Proteins||Localization||See full Fluorescent Protein Guide|
For more information about tags, including amino acid sequences, see our list of common tags.Back to Top
Regardless of your delivery method, it's unlikely that all of your cells will take up your plasmid. Thus, many plasmids have markers on them so that you can find or select for only the cells that received the plasmid.
|Selectable Marker||Typical Host Organism||Representative Empty Backbones|
Reporters, shRNA expression, transgenics and genome modification
|Element||Details||Representative Empty Backbones|
|Promoter||Measure promoter strength||
|shRNA/RNAi||For gene silencing experiments|
|Transgenic||Expression in organisms||