Fibronectin, stretching

Erickson HP. Reversible unfolding of fibronectin type III and immunoglobulin domains provides the structural basis for stretch and elasticity of titin and fibronectin. Proc Natl Acad Sci USA 1994 91 10114-10118. 

Connective tissue, such as tendon and cartilage, differs from other solid tissues In that most of Its volume Is made up of extracellular matrix rather than cells. This matrix Is packed with Insoluble protein fibers and contains proteoglycans, various multladhesive proteins, and hyaluronan, a very large, nonsulfated GAG. The most abundant fibrous protein In connective tissue Is collagen. Rubberlike elastin fibers, which can be stretched and relaxed, also are present In deformable sites (e.g., skin, tendons, heart). As discussed later, the fibronectins, a family of multladhesive matrix proteins, form their own distinct fibrils In the matrix of some connective tissues. Although several types of cells are found In connective tissues, the various ECM components are produced largely by cells called fibroblasts. 

Here, we report on single-molecule stretching of native fibronectin and the influence of the compatible solutes ectoine and sarcosine on the mechanical properties, as revealed by the unfolding of the individual subunits and the overall persistence length of the macromolecule [131], In accordance with the preferential exclusion model, we found a significant stabilization of the protein structure in the presence of osmolytes but not an increase in unfolding forces. 

The 3 MDa protein titin was the focus of many of the first SMFS investigations into protein unfolding [221]. Titin is composed of multiple-tandem repeats of Ig and fibronectin Ill-like domains [218]. Figure 15 depicts a typical force-distance cmve obtained from stretching titin 127 using SMFS. Each individual... 

---