Archives

  • 2026-06
  • 2026-05
  • 2026-04
  • 2026-03
  • 2026-02
  • 2026-01
  • 2025-12
  • 2025-11
  • 2025-10

    • Cy3-UTP: Photostable Fluorescent RNA Labeling Reagent for...

    2026-01-02

    Cy3-UTP: Photostable Fluorescent RNA Labeling Reagent for Quantitative RNA Biology

    Executive Summary: Cy3-UTP is a Cy3-modified uridine triphosphate designed for efficient incorporation into RNA during in vitro transcription, enabling high-sensitivity fluorescence-based detection and tracking of RNA molecules (APExBIO B8330). The Cy3 dye exhibits high brightness and photostability, supporting quantitative imaging and kinetic analyses in RNA biology (Cy3TSA). Site-specific RNA labeling with Cy3-UTP facilitates real-time studies of RNA folding, localization, and RNA-protein interactions, leveraging technologies such as stopped-flow fluorescence and FRET (Wu et al., 2021). The reagent’s aqueous solubility, triethylammonium salt form, and storage recommendations (-70°C, protected from light) ensure usability and long-term reliability (APExBIO). Benchmarks indicate robust performance in multiplexed live-cell imaging and single-molecule kinetic assays.

    Biological Rationale

    RNA molecules mediate essential regulatory, catalytic, and structural functions in all living cells. Fluorescent labeling of RNA enables visualization and quantitative analysis of RNA localization, trafficking, and dynamics in vitro and in vivo (Wu et al., 2021). Cy3-UTP incorporates the Cy3 dye—a fluorophore with excitation at ~550 nm and emission at ~570 nm—directly into RNA transcripts by enzymatic synthesis, creating molecular probes that are both photostable and sensitive (Cy3TSA).

    Labeling RNAs with Cy3-UTP supports detection and quantification in applications such as RNA-protein interaction studies, endosomal trafficking, and gene expression analysis. Cy3-UTP’s compatibility with in vitro transcription systems allows for site-specific or random incorporation, enabling advanced experimental designs including single-molecule studies and kinetic analyses (Wu et al., 2021).

    Mechanism of Action of Cy3-UTP

    Cy3-UTP is a chemically synthesized analog of uridine triphosphate, covalently linked to the Cy3 fluorophore. During in vitro transcription, RNA polymerases recognize Cy3-UTP as a substrate, incorporating it into RNA strands in place of natural UTP. The incorporated Cy3 moieties retain their fluorescence properties, enabling detection via excitation at 550 nm and emission at 570 nm (Cy3TSA).

    The triethylammonium salt form ensures high solubility in aqueous transcription buffers. The photostability of Cy3 allows for extended imaging and kinetic experiments without significant photobleaching. The structural integrity of labeled RNA is maintained, making Cy3-UTP suitable for downstream applications such as hybridization, protein binding, and structural studies (BMS-833923).

    Evidence & Benchmarks

    • Cy3-UTP enables real-time, single-nucleotide resolution tracking of riboswitch conformational changes via stopped-flow fluorescence (Wu et al., 2021, https://doi.org/10.1016/j.isci.2021.103512).
    • Incorporation of Cy3-UTP into RNA during T7 RNA polymerase-mediated in vitro transcription yields transcripts with high labeling efficiency and preserved biological activity (16-RNA-Labeling).
    • Cy3-labeled RNA demonstrates superior photostability compared to fluorescein-labeled analogs, allowing for prolonged quantitative imaging (Cy3TSA).
    • Fluorescently labeled RNA generated with Cy3-UTP supports FRET, fluorescence anisotropy, and co-localization assays in RNA-protein interaction studies (Wu et al., 2021, DOI).
    • Cy3-UTP's triethylammonium salt is stable when stored at -70°C, protected from light, with no significant degradation observed over several months (APExBIO).

    Applications, Limits & Misconceptions

    Cy3-UTP is widely applied in:

    • In vitro transcription RNA labeling: Enabling preparation of fluorescently tagged RNA for imaging and detection.
    • RNA-protein interaction studies: Permitting direct observation and quantification of binding events.
    • Fluorescence imaging of RNA: Supporting live-cell and fixed-cell visualization of RNA localization, trafficking, and dynamics (CP-809101 Hydrochloride, which primarily focuses on multiplexed imaging strategies; this article extends the discussion to kinetic and mechanistic analyses).
    • RNA detection assays: Providing high specificity and sensitivity for quantitative measurements.
    • Mechanistic RNA biology research: Facilitating studies of conformational changes, folding, and molecular interactions (R110 Azide 6-Isomer; this article provides updated benchmarks on kinetic analyses).

    Common Pitfalls or Misconceptions

    • Not suitable for in vivo transcription labeling in living cells: Cellular uptake of nucleotide analogs is limited; Cy3-UTP is designed for in vitro transcription workflows.
    • Photobleaching is not eliminated: While Cy3 is highly photostable, excessive illumination or improper storage can still cause signal loss.
    • Not compatible with all RNA polymerases: Some polymerases may exhibit reduced efficiency or altered specificity with bulky nucleotide analogs.
    • Long-term storage of Cy3-UTP in solution is discouraged: Degradation is possible; prepare aliquots and store at -70°C, protected from light (APExBIO).
    • Over-labeling may disrupt RNA secondary structure or function: Optimal labeling ratios should be empirically determined for each application.

    Workflow Integration & Parameters

    Cy3-UTP is supplied by APExBIO as a triethylammonium salt (SKU: B8330), soluble in water and suitable for transcription reactions. For in vitro RNA synthesis, Cy3-UTP is substituted for a portion of natural UTP (typically 10–50% of total UTP, final concentration 0.1–1 mM) in standard RNA polymerase protocols (16-RNA-Labeling). Transcription is performed at 37°C in transcription buffer (pH 7.5–8.0) for 1–4 hours. Labeled RNA is purified by standard methods (e.g., spin columns, PAGE).

    For imaging applications, Cy3-labeled RNA is excited at 550 nm and emission is collected at 570 nm. Photostability allows for repeated imaging with minimal signal loss. Storage recommendations are critical: stock solutions should be aliquoted and stored at -70°C, protected from light. Immediate use after thawing is advised to prevent degradation (Cy3-UTP product page).

    Integration with single-molecule and multiplexed imaging setups is supported, as is compatibility with downstream hybridization, FRET, and binding assays. This article clarifies protocol optimizations and troubleshooting strategies not extensively covered in BMS-833923 (which focuses on endosomal trafficking and delivery).

    Conclusion & Outlook

    Cy3-UTP provides researchers with a robust, photostable, and highly sensitive reagent for fluorescent RNA labeling. Its integration into in vitro transcription workflows accelerates quantitative, mechanistic, and kinetic studies in RNA biology. Future applications may include expanded multiplexed imaging, real-time tracking of RNA in complex systems, and integration with advanced single-molecule techniques. For detailed specifications and ordering information, consult the APExBIO Cy3-UTP (B8330) product page.