ABSTRACT
This chapter outlines the understanding of the components of basement membranes. Tumors have proven useful sources of basement membrane components. All basement membranes contain a special collagen type, Type IV, which is considered to be the major structural component. Soluble forms of Type IV collagen can be extracted with acidic solvents from the matrix of the EHS tumor, and from bovine lens capsule. Pepsin and other proteases are used to dissolve otherwise insoluble collagen. Type IV collagen does not precipitate as readily as other collagen types from solution under physiological conditions, and this difference has been exploited in separating the collagen types by thermal gelation. Type V collagen shares some features of interstitial and of basement membrane collagens. Intima collagen is resistant to digestion by bacterial collagenase and shows a biphasic thermal melting profile of the triple helix similar to that described for the long form of 7-S collagen.
