FIGURE 1.

Modular structure of sponge and sea anemone fibrillar collagens and of choanoflagellate collagen-like proteins. A–C, the general modular architecture of human members of the three fibrillar collagen clades (A), sponge (B), and sea anemone (C) α chains is depicted. For each α chain, the Arabic numbers under their domain architecture indicate the lengths in amino acids of the major triple helices. For the sponge fibrillar collagens chains, the Arabic numbers above the glycine substitutions and Gly-Xaa-Yaa-Zaa imperfections represent their precise location according to their numbering in the major triple helix. Under the A. queenslandica α chains, the solid lines represent regions confirmed by EST and RT-PCR sequences, and the dashed lines indicate that these sequences were deduced from genomic analysis. Amq, marine demosponge A. queenslandica; Emu, freshwater demosponge E. mülleri; Nve, starlet sea anemone N. vectensis;?, undetermined sequence. D, putative proteins including triple helical or COLF1 (C-propeptide) modules present in the choanoflagellate M. brevicollis. The accession numbers of the predicted M. brevicollis proteins are indicated below their modular representation. The Arabic numbers under the triple helix indicate their lengths in amino acids. In this figure, the different modules are not represented to scale.