Fluorescent proteins (FPs) offer scientists a simple yet powerful way to tag cellular proteins and investigate protein localization, interaction, and expression. However, one caveat of FP-protein fusions (FP-chimeras) is that they undergo normal protein turnover. FP-chimeras are continuously synthesized and degraded within the cell, so at any given time, an FP-chimeric protein may be at any one of many stages of synthesis and degradation. For this reason it is virtually impossible to determine specific protein turnover or temporal expression using standard FP-chimeric proteins.
What is an Aptamer?
Nearly 30 years ago, two independent groups, led by Jack Szostak and Larry Gold, developed methods for selecting and amplifying RNA sequences that could bind very specifically to target molecules. Using a technique called systematic evolution of ligands by exponential enrichment (SELEX), some 1010 oligonucleotides could be screened for their affinity to a wide range of non-nucleotide targets. These RNA molecules, which could bind their targets with high specificity and affinity, were eventually called aptamers, from the Latin aptus, meaning “to fit”. SELEX could be used to classify DNA aptamers as well, and over the course of the next two decades, these nucleotide-based ligand binders would prove to be highly adaptable tools.
Quick Announcement from the Plasmids 101 Team: In preparation for the release of Addgene's Fluorescent Protein eBook - our next couple of plasmids 101 posts will gain a healthy, fluorescent glow. Stay tuned for more fluorescence-based Plasmid 101 posts in the coming weeks!
In biology as in life, more is often better. More transcription factor binding sites in a promoter lead to higher transcriptional activation. Multiple nuclear localization signals (NLS) increase protein import into the nucleus. In developing their SunTag technology, the Vale and Weissman labs took this biological lesson and created a system to amplify fluorescent signals. Named for the "stellar explosion SUperNova," SunTag can help you turn up the brightness in your fluorescent imaging experiments.
Here at Addgene, we often refer to plasmids as lab or experimental tools. They certainly are very handy in research, but where did these tools come from and why do they exist in nature? Read on to learn more about environmental plasmids, and how they’ve helped us develop molecular biology tools for the lab.