Minor Proteins of Basement Membranes, Minor Collagens of the Basement Membrane Zone

This chapter discusses the minor proteins of basement membranes (BM) and minor collagens of the basement membrane zone. Several proteins or glycoproteins are considered to be basement membrane proteins, often because they are secreted by basement membrane producing tumors, although they are also largely found in tissues other than basement membranes. Some of them are only partially characterized. The chapter presents some examples of the minor proteins, which are commonly detected in BMs and may participate either in their structure or in their binding to the surrounding tissues. The chapter discusses a study in which a small acidic glycoprotein was extracted from mouse Engelbreth–Holm– Swarm (EHS) tumor and Reichert's membrane and termed as “BM‐40” on the basis of its M r 40,000. Type IV collagen is the only collagen specific for basement membranes. There are several other types of collagens that are located in the basement membrane, are associated with the basement membrane or more or less participate in the composition of basement membranes, or serve to anchor basal lamina to the neighboring connective tissue.