Fig. 8. SAD-1 PDZ-binding site is required for neuronal polarity but not for synaptogenesis. (A) SAD-1 lacking the PDZ-binding site rescues synaptic morphology defects. juIs1 puncta along the dorsal nerve cord of wild-type animals, sad-1 mutants and sad-1 animals expressing either SAD-1 (sad-1+SAD-1) or SAD-1 lacking PDZ binding site (sad-1+SAD-1DKV) from pan-neuronal Punc-115 are shown. (B) SAD-1DKV site fails to rescue sad-1 polarity defects in VD neurons. Pictures of dorsal synapse morphology after unc-30 RNAi in wild-type animals, sad-1 mutants and sad-1 animals carrying the SAD-1 rescuing construct are shown. (C) Quantification of ectopic dorsal-puncta number in animals treated with unc-30 RNAi (n=15, P<0.001 all versus wild type). (D) Both SAD-1-long (sad-1+SAD-1(l)) and -short (sad-1+SAD-1(s)) isoform cDNAs expressed from Punc-25 rescue synapse morphology defects. Morphology of juIs1 puncta in the dorsal nerve cords of L4-stage animals is shown. (E) Only SAD-1-longisoform cDNA rescued the VD polarity defects of sad-1 mutation. Pictures of the dorsal synapses in animals carrying the same expression arrays as in D after unc-30 RNAi. (F) Quantification of ectopic dorsal synapse number by VD neurons of animals treated with unc-30 RNAi in E (n=15, P<0.001 versus wild type). Scale bar: 5 µm in A,D.