ChromoBlog

Bispecific T cell engagers are bispecific antibodies designed to link T cells with cancer cells. The simultaneous binding of the bispecific antibody to T cell and tumor cell initiates the activation of the T cell. For this purpose, the bispecific antibody carries two antigen binding domains against the T cell (often CD3 T cell receptor) and against a cell surface protein of the tumor cell.

ChromoTek offers two bispecific T cell engagers to beta-testers:

Immunostaining in HeLa cells low expressing Tubulin-GFP.
Left: GFP signal of Tubulin-GFP (green) and DAPI stain (blue);
Right: Tubulin-GFP detection by GFP-Booster coupled to Alexa Fluor 647

We currently offer our GFP- and RFP-Booster conjugated to two different far-red dyes:

Alexa Fluor® 647 and  ATTO647N.

Nanobodies are the binding domains of heavy chain only antibodies from Camelids. Nanobodies can be recombinantly produced in bacterial and other animal-free expression systems depending on the actual Nanobody construct. In contrast, classical IgG antibodies are composed of two heavy chains and two light chains and are traditionally produced using hybridoma technlogies or are isolated from a host’s blood.

Introduction

Fluorescent proteins (FPs) have been used as protein tags since the mid-1990s mainly for cell biology and fluorescence microscopy. These tags have not only revolutionized cell biology by enabling the imaging of almost any protein, they are also used in biochemical applications. An important example is the immunoprecipitation and affinity purification of FP-tagged proteins, which was enabled by the development of affinity resins with high yield, purity, and affinity such as ChromoTek’s Nano-Traps (https://www.chromotek.com/products/detail/product-detail/nano-traps/).

In this blog we provide a review of

• green fluorescent proteins
• red fluorescent proteins
• self-labelling proteins, that require the covalent coupling of a fluorescent molecule

Jellyfish Green Fluorescent Protein (GFP) and its derivatives are still the most frequently used fluorescent proteins in biomedical research. Recently, additional green fluorescent proteins have been discovered in higher animals such as crustaceans and lancelets. These FPs share a common fold, but diverge widely in their primary sequence. Thus, they require novel, dedicated antibody research tools. Here is an overview about EGFP (the most commonly used GFP derivative), TurboGFP and mNeonGreen.

A collaboration between ChromoTek GmbH and Ludwig-Maximilians-University Munich (Germany) has yielded a novel nanobody that sheds new light on an important protein complex called INO80. This work was recently published in the high-impact journal Nature Structural & Molecular Biology (Knoll et al. 2018).

You may have noticed the recent publication “A peptide tag-specific nanobody enables high-quality labeling for STORM imaging” of Virant et al (2018) in Nature Communications doi: 10.1038/s41467-018-03191-2, where for the first time a peptide-tag specific Nanobody was applied in dSTORM imaging: The authors have described and discussed the performance of a BC2 peptide-tag specific Nanobody to image BC2 peptide tag fusion proteins in super resolution microscopy, i.e. dSTORM. This Blog features that BC2 peptide-tag specific Nanobody, which ChromoTek markets under the names Spot-Label® and Spot-Trap®. In addition, this Blog figures the significantly improved version of the BC2 peptide -tag, which is called Spot-Tag®.

ChromoTek’s Marketing Manager Dr. Christoph Eckert has been interviewed by Biocompare, the buyers’ guide for life scientists, on labels for super resolution microscopy.