GPCR-activation Based (GRAB) Sensors
Neurotransmitters are key neurochemicals that regulate many neural processes, including cognition, emotions, memory and sleep, by influencing circuits in the brain. Understanding the release and distribution of neuromodulators in behavior-modulating animals is critical to understanding the various functions of these molecules. However, there is a lack of new tools that can monitor these compounds in the temporal, spatial and concentration ranges related to these brain processes. Filling this technological gap is one of the most urgent needs in neuroscience research.
To address this issue, Creative Biolabs has developed a new tool platform for long-term, non-invasive monitoring of neuromodulators with millisecond, subcellular and nanomolar resolution. Building on our previous experience in developing these tools, we now provide a series of genetically encoded GPCR-activated (GRAB) fluorescent indicators for neuroscience research. Specifically, we provide various GPCR-based neurotransmitters sensors for the dection of ACh, DA, 5HT, EP, NE and GABA in the major model systems, including worms, flies, rodents, and increasingly primates. These GPCR-based sensors can monitor the dynamics of neurochemicals in behavioral animals with high temporal and spatial resolution.
Princinple of GPCR‐based sensors
The most critical feature of GPCR as an engineered fluorescent sensor scaffold based on circular-permutated fluorescent protein (cpFP) is its conformational change, which occurs after being activated by a specific ligand. Specifically, GPCR has several conformational states, including inactive, partially active and fully active states. The largest conformational difference is transmembrane helix 5 and 6. Ligand binding and subsequent G protein interaction stabilize the protein in an active conformation, leading to downstream signal transduction. Capitalizing on this conformational change, the GRAB sensor is designed by combining a ligand binding protein (as a "sensing scaffold") with cpFP. Using the GRAB sensor, the cpGFP part is inserted into the third intracellular loop of the GPCR; this loop connects transmembrane helices 5 and 6, and undergoes a large conformational change after ligand binding, which causes a change in fluorescence (Figure 2). Since most GPCRs have a common activation mechanism, in principle, this strategy can be extended to develop sensors for different neurochemical substances.
Fig.2 Princinple of cpFP-based GRAB sensors.
Features of GRAB sensors
1) High sensitivity
2) High specificity
3) High temporal and spatial resolution
4) High signal-to-noise ratio
6) No additional testing equipment is required, which is consistent with the calcium signal detection system.
Available GPCR sensors at Creative Biolabs
In addition to ready-made neurotransmitter sensors, we also provide design and construction services for neurotransmitter sensors. If you are interested in our services, please send an email to contact us, and our team will get back to you as soon as possible.