Figure 3

Sequence of the C-terminal propeptide of the proα1(III) chain. The sequence begins with 1 (residue 1222 of the chain) that is the site of the enzymatic cleavage from the remainder of the chain. The last residue, 245 in this figure, is position 1466 of the proα1(III) chain, the last encoded residue of the chain. There are eight cysteine residues in the chain (numbered 1–8). There are three sets of intrachain disulfide bonds (1–4, 5–8 and 6–7). Cysteine residues 2 and 3 are involved in interchain disulfide bonds that stabilize the trimer. The glycine (G) that precedes cysteine 3 is substituted by glutamic acid (E) in the products of one of the mutant alleles. ▴, regions of α-helix; ▪, regions of β-sheet; •, residues involved in coordinating a Ca⁺⁺ ion. The standard single letter code is used to designate amino acids. The chain-association region is underlined and the regions of the structure as determined by Bourhis et al¹³ are described (stalk, base, and petal). This figure is adapted from Figure 1 along with information from publication by Bourhis et al, and the spacing of residues is retained to account for regions that are missing in the C-propeptides of other fibrillar collagen genes.