Holding It Together: a Closer Look at Collagen

There are many ubiquitous proteins that can be found in many organisms throughout nature. Actin and myosin are two examples of "universal" proteins. Actin and myosin are proteins that make contraction, and therefore movement possible. Most organisms depend on movement in their quest to survive. It is logical, therefore, that most organisms' genomes contain genes that code for actin and myosin.

Another example of a ubiquitous, or "universal" protein is collagen. Collagen is a vital protein as it serves as a indispensable constituent of connective tissue. Most connective tissue cells (areolar, dermis, cartilage, and bone, as examples) secrete some form of collagen (to date, twelve different types of collagen have been discovered). Collagen acts to link structures and hold them together. It is found in the basal lamina, in bones, in tendons, and in various other locations.

As proof of collagen's ubiquitous existence in nature, it has been found and isolated in a variety of organisms which have had their genomes thoroughly studied: Gallus gallus (chicken), Caenorhabditis elegans (worm), Drosophila melanogaster (fly), Mus musculus (mouse), and Homo sapiens (human). The following are links to the protein (amino acid) sequences for collagen in each of these organisms (the source for each image is found in small print below each image):

Additionally, a three dimensional look at collagen is provided. In pages to come, the three dimensional structure of this very important protein will be studied in more depth. For now, this image serves as a useful guide in the overall configuration of collagen.

• Rasmol Image of Collagen (Type VI)