Fig. 1. (A) Alignment of Spaw and other Nodal-related proteins. Black arrowheads indicate putative cleavage sites between the prepro and mature ligand domains (RXRR). Open arrowheads indicate position of a conserved intron. Arrows indicate peptide stretches where the corresponding nucleotide sequences are complementary to the morpholinos Spaw-MO1 and Spaw-MO2. Heavy underlining indicates nodal-specific motifs (NAYRCEG and PTNHAY). The boxed region highlights the split cysteine pattern (CXXC) that differentiates the Xnr1/Sqt subclass and Nodal/Cyclops subclass (XXCC). (B) Amino acid identity (%) between the spaw prepro domain or mature domain and the corresponding domains of Sqt, Cyclops and Xnr1.