A comparative study of structural properties of fibronectin and its 180 kDa fragment

Abstract

Fibronectin from human plasma and its 180 kDa fragment which retained collagen-binding, cell-attachment and heparin-binding activities, were studied by velocity centrifvgation and 'H-NMR methods. The tibronectin hydrodynamic radius strongly increased at pH 11 while the hydrodynamic properties of the fragment did not change noticeably. 'H-NMR spectroscopy also showed differences in the molecular properties of fibronectin and its 180 kDa fragment. Under physiological conditions the structure of fibronectin differs from that of its 180 kDa fragment. At pH 11 and in 4 M urea no differences in their structures are observed. It is suggested that interdomain and intersubunit interactions play an important role in maintaining the native conformation of intact tibronectin. Fibronectin 180 kDa fibronectin fragment 'H-NMR

Model of fibronectin tertiary structure based on studies of interactions between fragments

“…Our sedimentation velocity constant of 12 reported here for the 190-kDa fragment as well as the work above clearly shows that the 190-kDa fragment can be dimeric under certain conditions. However, other work (Bushuev et al, 1985) suggests a much smaller S20,w value of 6.8 for a 180-kDa fragment prepared by trypsin digestion. This fragment may differ from our 170/190-kD fragment, since tryptic proteolysis is known to remove a 31-kDa carboxyl-terminal fragment, perhaps the Fib II fragment, as well as the amino-terminal 29-kDa fragment (Gold et al, 1983).…”

Modulation of Cell‐Extracellular Matrix Interactionsa

“…FN has a compact conformation in solution 26‐28 and, therefore, must be unfolded in order for FN‐FN interactions and fibril formation to progress. Unfolding is presumably initiated by binding to cell‐surface integrin receptors.…”