Figure 2.

Amino acid sequence alignment of TGF-βs between lampreys and humans. (A) Alignment of the prodomains of TGF-βs between lampreys and humans. The sequence features of the straitjacket domain and the arm domain are shown above the alignment. Conserved cysteine residues involved in the formation of the TGF-β large latent complex (LLC) are highlighted in the red box, green box, and green box, respectively. The Arg-Gly-Asp (RGD) sequences in human TGF-β1 and TGF-β3 are highlighted by black underline. The Gly-Gly-Asp (GGD) sequences in lamprey TGF-β3 are highlighted by purple underline. (B) Alignment of the ligand domains of TGF-βs between lampreys and humans. The eight conserved cysteine residues forming four intramolecular disulfide bonds are marked by the red arrows above the alignment. The other cysteine residue involved in the formation of intermolecular disulfide bonds that link the two monomers into a dimer is marked by the green arrow. (C) Protein structure comparison of TGF-β2 mature peptide between Japanese lamprey and human. The molecular model of lamprey TGF-β2 mature peptide homodimer was built by homology modeling of SWISS-MODEL based on the human TGF-β2 (PDB code 2tgi.1.B). The two monomers of TGF-β2 are shown in blue and green, respectively. Two views are displayed, rotated by 90° with respect to each other.