Amino acid sequences of LRRNT in known VLR molecules.

Representative VLR sequences from lampreys and hagfish were aligned, and the number of residues between β-strands, β1 and β2, was counted. Frequency of sequences with a given number of residues between β1 and β2 (shown on the right side of the figure) was calculated using publicly available sequences. Note that all known lamprey VLRC sequences have eight residues between β1 and β2 (highlighted in yellow). The number of corresponding residues is four in VLRA, and >90% of VLRB sequences have two residues (highlighted in green). In hagfish VLRC, amino acid residues which form 3₁₀-helices are highlighted in orange. VLR sequences are from sea lamprey (Pm, Petromyzon marinus), Japanese lamprey (Lj, Lethenteron japonicum), brook lamprey (Lp, Lampetra planeri), inshore hagfish (Eb, Eptatretus burgeri), and Pacific hagfish (Es, Eptatretus stoutii). VLR molecules were named according to the new nomenclature. Thus, EbVLRC and EsVLRC correspond to the previously reported EbVLRA and EsVLRA molecules, respectively. EsVLRA represents the newly described VLR [25].