Alignment of neurotrophin Cys knots to Spz C-106 sequences. An arrow head (above alignment) indicates where partial Spz6 sequences were removed. I to VI designate conserved "Cys knot" cysteines (white on black). "H" (below alignment) indicates a hydrophobic site. Cys unique to Spz subfamilies are in grey. Highlights indicate frequent characteristic residues of either Spzs (red tones) or neurotrophins (blue-green tones). Canonical invertebrate deuterostome neurotrophins (amphioxus and sea urchin NT) are separated from those belonging to the 2nd sea urchin neurotrophin "NT2" and the two acorn worm ESTs ("NTa" and "NTb"). Dmagna: Daphnia magna. Dappu: Daphnia pulex.