Excerpt from the ClustalX alignment of full length fibrillin focusing on the unique regions and the subsequent EGF4 domain.

<p>The end of TB1, the unique region, and the EGF4 domain found characteristically in mammalian fibrillins are indicated on the bottom. For invertebrate organisms, the cbEGF-like (purple box), and the new cbEGF domain (orange box) are highlighted, and cysteine residues are circled in red in these domains. The relative numbers of the cysteine residues within the respective EGF domain is indicated on top. Note that the unique region does not exist in invertebrate fibrillin proteins, and is instead replaced by a cbEGF-like domain. The non-calcium binding EGF4 domain that typically follows the unique region is replaced in invertebrate fibrillins by a cbEGF domain.