Regulation of Pathways

Pictures of fibrinogen

Fibrinogen as two each of three subunits. In the initial picture below each is colored differently. The unusual thing here is the shape of this protein. notice it very long and narrow conformation. The two "halves" of the protein are held together by very few contacts overall. Each group of three subunits is a long helix that are coiled around each other. Thrombin IIa cleaves out short peptides of fibrinogen to make fibrin. Fibrin molecules associate in a network, like that modeled by two fibrinogen here on this page. Then Factor XIIIa bonds the Lys of one fibrin to a Gln on the neighbor to form an isopeptide bond. (The pictures that you can select below are all modeled with fibrinogen. Their orientation is meant to represent only the relative positions of two molecules in the network. In another picture, all the Lys of one molecule are highlighted while all the Gln are highlighted on the other. This is not meant to represent the ones that are crosslinked but to show that the crosslinks are most likely in regions of protein - protein contact).
individual fibrinogen  Coiled Coil  two 'fibrin'  Lys and Gln highlighted