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Fluorescent Proteins 101: Visualizing Subcellular Structures & Organelles

Posted by Susanna Bachle on Jun 22, 2017 10:30:00 AM

The same way the human body is made up of organs, cells comprise compartments and structures, called organelles. Take a sneak peak inside a cell with the images from the Allen Cell Explorer (1).

When studying the function of a protein or its role in a disease, researchers often isolate proteins of interest and examine them using biochemical methods thus removing the context of the cell. However, much knowledge about functionality can be gained by understanding the location and transport of the protein within a living cell. Analyzing differences in protein localization and transport between healthy and diseased states can also provide interesting insights into disease mechanisms and protein function.

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Topics: Fluorescent Proteins, Fluorescent Proteins 101

Choosing the B(right)est Fluorescent Protein: Aggregation Tendency

Posted by Guest Blogger on Jun 15, 2017 10:30:00 AM

This post was contributed by guest bloggers Joachim Goedhart and Marieke Mastop from the Section of Molecular Cytology and Van Leeuwenhoek Centre for Advanced microscopy, University of Amsterdam.

The previous two posts in this series described a practical approach to selecting a bright fluorescent protein and a photostable fluorescent protein. In the third post of this series, we will discuss how to select a non-aggregating fluorescent protein.

In the jellyfish Aequorea victoria, AvGFP forms a homodimer. In corals, the red fluorescent proteins form tetramers. In general, fluorescent proteins have a natural affinity and a tendency to form higher order aggregates. This property can be tolerated in some applications (e.g. labeling of cells or tracking promotor activity), but it is problematic in applications in which the fluorescent protein is used as an inert protein module. This is explained in more detail here. There are a variety of methods that can be used to measure your fluorescent protein’s propensity to aggregate. The basics and pitfalls of these experiments are discussed here.

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Topics: Fluorescent Proteins, Fluorescent Proteins 101

Choosing the B(right)est Fluorescent Protein: Photostability

Posted by Guest Blogger on Jun 8, 2017 10:30:00 AM

This post was contributed by guest bloggers Joachim Goedhart and Marieke Mastop from the Section of Molecular Cytology and Van Leeuwenhoek Centre for Advanced microscopy, University of Amsterdam.

The previous post in this series described a practical approach to selecting a bright fluorescent protein. In the second post of this series, we will discuss how to select a photostable fluorescent protein.

Photobleaching is the irreversible destruction of a fluorophore under the influence of light. Any fluorescent molecule will photobleach at some point. For live-cell imaging, it is desirable to have fluorescent proteins that are photostable. On top of photobleaching, fluorescent proteins may display reversible intensity changes (Shaner et al, 2008; Bindels et al, 2017) and photoswitching (Kremers et al, 2009), which usually are undesired properties. In the ideal situation, a fluorescent proteis should emit a stable fluorescence signal, showing no or little deterioration or change of the signal during the course of the experiment.

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Topics: Fluorescent Proteins, Fluorescent Proteins 101

A Practical Approach to Choosing the B(right)est Fluorescent Protein

Posted by Guest Blogger on Jun 1, 2017 10:30:00 AM

This post was contributed by guest bloggers Joachim Goedhart and Marieke Mastop from the Section of Molecular Cytology and Van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam.

Before you decide which car you want to buy, it is worthwhile to test-drive a couple of candidates. Before you buy a new microscope, it is smart to look at (and through) a couple of models. Before you start a new project with fluorescent proteins, the best advice is to try a couple of promising variants to check how they perform under your experimental conditions. This is time well spent and, if you do it right, can be (part of) figure 1 of your next paper or thesis. This series of posts explains how to critically assess the reported properties of fluorescent proteins, how to do a head-to-head comparison of fluorescent proteins and how to make a well-informed decision on the best fluorescent protein for your application.

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Topics: Fluorescent Proteins, Fluorescent Proteins 101

Fluorescent Proteins 101: Fluorescent Biosensors

Posted by Jessica Welch on May 18, 2017 10:30:00 AM

Addgenie Mary Gearing contributed to the content of this article.

Biosensors (‘biological sensors’) are biological tools that monitor a process or detect a given molecule. The sensor component is usually a protein that undergoes a conformational change in response to the molecule it detects. This change then generates a reporter signal. Reporter signals may be electrochemical or light-based, with luminescent and fluorescent reporters being especially popular. We’ll give you an introduction to fluorescent biosensors, but keep in mind that there is a lot of variety in how biosensors work, and you should always check the associated publication for the specifics of your chosen plasmid.

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Topics: Fluorescent Proteins, Fluorescent Proteins 101, Fluorescent Biosensors

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