Everybody really wants to use a detection probe that does not influence its target. For measurement of actin and actin-related functions there are a number of actin visualization probes and techniques available that researchers can select. Hence, one should only apply such actin visualization probes, which do not alter actin dynamics. How do the actin probes for visualization perform? Which probes do interfere with function and which probes do not? Robert Grosse and his team from the Institute of Pharmacology at the Biochemical-Pharmacological Center (BPC), University of Marburg, Germany took the effort and systematically looked into detection technologies of actin filaments in order to avoid potential pitfalls. In the recently published mini review/poster “Actin Visualization at a Glance” (Melak et al. 2017) they have discussed the pros and cons of current probes to visualize actin filaments, i.e. Phalloidin, LifeAct, Utrophin, F-tractin, SiR-actin, GFP-actin, tagged actin, and Actin Chromobody® (see table 1 and figure 1 below).
The ChromoTek Actin Chromobody is a live-cell probe for visualization of the actin cytoskeleton and monitoring its dynamics. The Actin Chromobody enables non-invasive labeling of actin microfilaments not only in mammalian cells, but also in cells and tissues of evolutionary distant species, such as Zebrafish (Panza et al. 2015) or plants (Rocchetti, Hawes, and Kriechbaumer 2014). The Z-stack shows confocal images of optical sections of Actin Chromobody in a Hela cell.
This time last spring we started marketing our Chromobody® plasmids. Our customers realized the impact of the technology and were immediately beginning to work with the Chromobodies®. Now, one year later the first papers are being published demonstrating the broad applicability of this intracellular fluorescent antibody technology:
The first is a paper in Molecular Cell by the Lindqvist Lab at the Karolinska Institutet in Stockholm, Sweden. They developed a FRET-based system for accurate quantification of fluorescence from single cells. By visualizing endogenous PCNA at replication foci with the Cell Cycle Chromobody® they nicely show that the mitotic entry network is linked to the completion of S phase. It does not depend on protein accumulation through G2 but is activated by mitotic phosphorylations at the end of S phase. The method they present allows analyzing live-cell as well as extracting temporal information from fixed cells based on endogenous marker proteins. (Akopyan, K.; Silva Cascales, H.; Hukasova, E., et al. Assessing kinetics from fixed cells reveals activation of the mitotic entry network at the S/G2 transition. Molecular cell. 2014, 53, 843-853. http://dx.doi.org/10.1016/j.molcel.2014.01.031)