HaloCaMP: Chemigenetic Calcium Indicators Using HaloTag and Janelia Fluor Dyes

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HaloCaMP: Chemigenetic Calcium Indicators Using HaloTag and Janelia Fluor Dyes

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A Modular Calcium Imaging Platform with Far-Red Brightness

Overview

HaloCaMP integrates circularly permuted HaloTag proteins with a range of Janelia Fluor (JF) dyes to form bright, modular calcium indicators for in vitro and in-cell imaging. This chemigenetic system offers far-red imaging, rapid labeling, and customizable readouts for neuroscience and cell biology.

Key Benefits

Red and Far-Red Imaging
- Enables imaging beyond GFP’s spectral range, compatible with deep-tissue setups.
Multiple JF Dye Options
- JF585 (orange): Highest ΔF/F₀ (~23× in vitro)
- JF635, JF639 (far-red): Bright and neuron-compatible
- JF629, JF630: Sensitive with low baseline for improved contrast
Neuron-Ready
- Expressed in hippocampal cultures and capable of reporting single action potentials.

Performance Highlights

Dye	Color	ΔF/F₀	Notes
JF585	Orange	23.2	Highest ΔF/F₀ in vitro
JF635	Far-Red	5–9	Strong neuronal performance
JF629	Far-Red	Moderate	Best with HaloCaMP1a
JF630	Far-Red	Moderate	Best with HaloCaMP1b