Myo1G regulates nodal receptor trafficking. a, b Spaw-GFP localization is similar in WT (n = 20) and MZ myo1g mutants (n = 17). H2B-RFP was injected as a tracer to ascertain that embryos that had received equal amounts of RNA (see Supplementary Fig. 11a for quantification). c A constitutively activated form of the Nodal signal transducer SMAD2 (CA-SMAD2) elicits similar responses in WT and MZ myo1g mutants. Box plots in c indicate mean values ± SD. d Myo1G-GFP is detected at the cell cortex and in intracellular compartments (n = 10). e, e’, e” Myo1G-GFP is present on endosomes positive for the TGFβ signaling adapter SARA (n = 24, see also Supplementary Fig. 12a, b). f–j MZ myo1g mutants present a reduced number of endosomes positive for the Nodal receptors Acvr2Aa-GFP (f, g, j, n = 13 WT and 13 MZ myo1g mutant embryos) and Acvr2Ba-GFP (h–j, n = 14 WT and 13 MZ myo1g mutant embryos). In j data points represent the mean number of endosomes per cell for a particular embryo and lines indicate the overall mean ± SEM. k, l MZ myo1g mutants and WT siblings present a similar number of CD44a-positive endosomes (n = 7 WT and n = 7 MZ myo1g mutant embryos, see Supplementary Fig. 11b for quantification). a, b, d–i, k, l, animal pole views, germ ring stage. Scale bars: 10 µm. All p values were obtained using non-directional statistical tests. Complete numerical and statistical information are provided in the Source Data files.
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