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Fc region binding peptide conjugated with attenuated cationic amphiphilic lytic peptide L17E trimer [FcB(L17E)3] was designed for immunoglobulin G (IgG) delivery into cells. Particle‐like liquid droplets were generated by mixing Alexa Fluor 488 labeled IgG (Alexa488‐IgG) with FcB(L17E)3. Droplet contact with the cellular membrane led to spontaneous influx and distribution of Alexa488‐IgG throughout cells in serum containing medium. Involvement of cellular machinery accompanied by actin polymerization and membrane ruffling was suggested for the translocation. Alexa488‐IgG negative charges were crucial in liquid droplet formation with positively charged FcB(L17E)3. Binding of IgG to FcB(L17E)3 may not be necessary. Successful intracellular delivery of Alexa Fluor 594‐labeled anti‐nuclear pore complex antibody and anti‐mCherry‐nanobody tagged with supernegatively charged green fluorescence protein allowed binding to cellular targets in the presence of FcB(L17E)3. [ABSTRACT FROM AUTHOR]

Heterochromatin protein 1α (HP1α) undergoes liquid–liquid phase separation (LLPS) and forms liquid droplets and gels in vitro, properties that also appear to be central to its biological function in heterochromatin compaction and regulation. Here we use solid‐state NMR spectroscopy to track the conformational dynamics of phosphorylated HP1α during its transformation from the liquid to the gel state. Using experiments designed to probe distinct dynamic modes, we identify regions with varying mobilities within HP1α molecules and show that specific serine residues uniquely contribute to gel formation. The addition of chromatin disturbs the gelation process while preserving the conformational dynamics within individual bulk HP1α molecules. Our study provides a glimpse into the dynamic architecture of dense HP1α phases and showcases the potential of solid‐state NMR to detect an elusive biophysical regime of phase separating biomolecules. [ABSTRACT FROM AUTHOR]

Keywords: antibodies; intracellular delivery; liquid droplet; liquid-liquid phase separation (LLPS); peptides EN antibodies intracellular delivery liquid droplet liquid-liquid phase separation (LLPS) peptides 19493 19493 1 08/28/21 20210901 NES 210901 B Large amounts of antibodies b can be rapidly delivered into cells from coacervates (liquid droplets) formed by mixing a fluorescently labeled antibody and a delivery peptide, as reported by Shiroh Futaki et al. in their Research Article on page 19804. The cover illustration shows a representation of the intracellular delivery of antibodies by coacervate. The cover illustration shows a representation of the intracellular delivery of antibodies by coacervate. [Extracted from the article]