Versatile Collagens in Invertebrates

摘要

Collagens, the most abundant proteins in our body, are the essential stuctural element of connective tissues such as skin, bone, and tendons. Many mammalian collagens (1)— the fibril-forming interstitial collagens (type I, II, III, and V) and basement membrane collagen (type IV), for example—can be traced back to early organisms like mussels, worms, and sponges (2, 3). In addition, invertebrates also contain other, unrelated collagens that serve specialized functions and have unusual domain organizations (see the figure). These include mini-collagens from hydra (4) and the longest known collagens, from annelids (5). A particularly fascinating example is the collagen from mussel byssus threads, described in this issue on page 1830 (6).