For Research Use Only. Not for Clinical Use.

Creative Biolabs has leading technical strength and professional team and has created a global innovative experimental platform. We are committed to providing our customers with half-life services in the drug development process such as half-life assay by Photoactivatable Fluorescent Proteins, expecting to bring more value to customers with rich technical resources and customized services.

Introduction of Photoactivatable Fluorescent Proteins

In the proteomic analysis of cell biology, fluorescent proteins and cellular proteins are often encoded by fusion to form fusion proteins, to locate and analyze the dynamics of proteins in living cells, such as green fluorescent proteins and their multicolor homologs. Recently, a novel methodology has emerged with the development of so-called photoactivatable fluorescent proteins (PAFPs). PAFPs are molecules that switch to a new fluorescent state in response to activation to generate a high level of contrast, which are capable of pronounced changes in their spectral properties in response to irradiation with light of a specific wavelength and intensity. Some PAFPs convert from a dark to a bright fluorescent state (photoactivation), whereas others change fluorescence color (photoconversion).

Fig.1 Spectral and photochemical properties of photoactivatable fluorescent proteins. (Lukyanov, 2005)

Applications of Photoactivation

• Pulse-chase photolabelling and tracking
  The three main levels of PAFP application are protein, organelle, and cell labeling. In contrast to the observation of fluorescently tagged objects by constant imaging, PAFPs allow the object to be tracked without the need for continual visualization. This feature greatly extends the spatio-temporal limits of studies of biological dynamics and reduces the photobleaching and phototoxicity problems of imaging procedures. Various cellular organelles can also be loaded with PAFP to show the transport, fusion, and fission events of individual organelles. The most important application of PAFPs is protein labeling. When fused to a protein of interest, PAFPs can provide detailed information about protein localization, turnover, and the direction and rate of trafficking in a living cell. This provides a tool for half-life analysis of protein drugs such as antibodies. By using PAFPs with distinct colors, it could be possible to assay the half-life of several drugs simultaneously.
• Detection of protein interactions
  PAFPs open new avenues for the study of protein-protein interactions using fluorescence resonance energy transfer (FRET). Using an irreversible PAFP as a donor, acceptor, or both in photoactivatable FRET (PA-FRET) microscopy would make it possible to study the spatio-temporal localization and interaction of fusion proteins simultaneously.
• Cellular imaging and sorting
  Using stimulated emission depletion, reversible PAFPs that can undergo numerous light-induced transitions between dark and fluorescent states could be used for live-cell imaging with a high spatial resolution at a low light intensity. In addition, PAFPs could also contribute to fluorescence-activated cell-sorting techniques, functioning as the extra colors that can be turned on to further differentiate between cell types.

Fig.2 Three levels of spatio-temporal labeling with photoactivatable fluorescent proteins. (Lukyanov, 2005)

After years of accumulation, Creative Biolabs has a solid foundation in drug half-life research. We are confident to provide high-quality half-life assay services for our customers. If you have any questions about half-life assay or photoactivatable fluorescent proteins, please contact us for more detailed information.

Reference

1. Lukyanov, K. A.; et al. Innovation: Photoactivatable fluorescent proteins. Nature reviews. Molecular cell biology. 2005, 6(11): 885-891.