“…The D4-D4 dimerization interface, as revealed in the crystal structures of hRobo2 D4-5 and hRobo1 D1-4 , includes several conserved residues, one of which is hRobo2 F357 / hRobo1 F394 (Figures S1 and S3). Previously, we found that a F357R substitution eliminates hRobo2 D4-5 dimer formation in AUC measurements (Yom-Tov et al, 2017) and, therefore, targeted the homologous SAX-3 F360 in the C. elegans AVM guidance model. As anticipated, the Pmec-7::sax-3 F360R transgene showed a loss-of-function phenotype, with only 30% of the total animals (n = 91) with a ''turn'' phenotype, 53% ''straight,'' and 16% other phenotypes.…”