[Association between the glomerular basement membrane and fibronectin as revealed by affinity chromatography ]

Though there is sufficient evidence that fibronectin is an integral extracellular matrix protein of the normal human kidney, the distribution and the interaction with structural proteins of the kidney have not been resolved. There are disagreements between investigators whether fibronectin is a component of the glomerular basement membrane or linked to it. We have been examining the interaction between the glomerular basement membrane and its components type IV collagen and laminin and fibronectin. Applying affinity chromatography we detected significant interaction between collagen type IV and laminin, and fibronectin on the other hand. The noncovalent interaction between collagen type IV and fibronectin was reversible after elution with 2 M urea, the association between laminin and fibronectin was even stronger and reversible applying 3 M urea for elution. The glomerular basement membrane-fibronectin interaction reflected the laminin pattern though minor binding sites at 1 M urea and 2 M urea could be detected. These interaction studies showed the chemical and thermodynamical possibilities and probability of the glomerular basement membrane and fibronectin linkage.