The objective of this proposal is to study the structure and organization of basement membranes. The first aim is to isolate basement membrane collagens from human placental tissue by pepsin solubilization. The second aim is to isolate the non-collagenous proteins from intact, detergent solubilized placental basement membranes, from membranes synthesized in placental tissue culture, and from the mixture of peptides obtained from pepsin digest of human placental tissue. The proteins will be purified by chromatography and characterized by amino acid and carbohydrate analysis. Antibodies will be raised to all isolated proteins and will be used as a tool in structural studies. We will produce cyanogen bromide peptides, order them by amino acid sequence analysis and then establish their amino acid sequence. Electron microscopy and x-ray diffraction will be done on intact basement membrane to search for periodic structures. Finally, the aggregation properties of the purified collagenous proteins and the effects of the non-collagenous proteins on such aggregation will be investigated.