Fig. 1

Synapse-specific distribution of Lrp4 β-gal in Lrp4-lacZ mice. a, b β-gal activity in the central region of muscle fibers. a Representative images of left ventral hemi-diaphragms of E13 lacZ/+ mice, which were stained whole-mount for β-gal activity (blue) and with Alexa fluor 594-conjugated α-BTX (referred to as α-BTX, red). Scale bar, 0.1 mm. b Central distribution of β-gal in lacZ/+ diaphragms. ****p < 0.0001, n = 7 mice per group, unpaired t-test. c Similar distribution of β-gal and AChR clusters in diaphragms at P42. Scale bar, 0.1 mm. d, e Quantification of the bandwidth of β-gal and AChR (d), the density of β-gal and AChR clusters (e). n = 6 mice per group, unpaired t-test. f Co-localization of β-gal cluster and AChR cluster in an EDL muscle fiber. Single muscle fibers of EDL were subjected to staining for X-gal and with α-BTX. Scale bar, 0.1 mm. g Superimposed β-gal and α-BTX intensity of single muscle fibers. Signals per 10 µm were averaged along muscle fibers by ImageJ and the central of AChR cluster was designated as point 0