Fig. 1: Polyamines form condensates with heparin.
From: Mast cell extracellular granules are bioactive condensates assembled by heparin and polyamine
a, Bright-field images of 5 μM heparin in 50 mM HEPES pH 7.4 buffer in the presence of cationic salts at the indicated concentrations. Scale bar, 10 μm. b, Left, condensation of 50 μM FITC-labeled heparin in the presence of increasing concentrations of spermidine and spermine. The clustering level of heparin was quantified as normalized variance of heparin fluorescence and the partition coefficient of heparin was quantified as the ratio of heparin fluorescence in the dense phase to that in the dilute phase (n = 15 individual images per group). Scale bar, 10 μm. c, Low-concentration arm of the phase boundary mapped in terms of heparin (abscissa) and spermine (ordinate) concentrations. The open circles are concentrations corresponding to the one-phase regime and solid circles correspond to concentrations that place the system in the two-phase regime defined by coexisting dense and dilute phases. d, Quantification of clustering level of heparin condensates as shown in c (n = 15 individual images/group). e, Fluorescence images of heparin–spermine condensates formed by 100 μM heparin (added 2 μM Cy5–heparin; magenta) and 10 mM spermine (added 2 μM BODIPY–spermine; green). Bottom right, quantification of partition coefficients (dense-phase intensity/dilute-phase intensity) of heparin and spermine in condensates in a histogram (n = 58 individual condensates). Scale bar, 10 μm. f, FRAP of heparin–spermine condensates. Right, time course of fluorescence recovery of Cy3-labeled heparin or BODIPY–spermine in condensates formed by a total of 50 μM heparin and 5 mM spermine (n = 17 (heparin) or 21 (spermine) individual condensates). Scale bar, 2 μm. Data are presented as the mean ± s.d. One representative experiment from three independent experiments is shown.
