Effect of the structural components of basement membranes on the attachment of teratocarcinoma-derived endodermal cells.

The effect of biochemically purified basement membrane components as mediators of cell attachment is studied in vitro using an endodermal PYS-2 cell line known to produce a basement membrane-like insoluble matrix. Fibronectin is shown to be as effective as laminin as an attachment-promoting protein, although the latter is a major product of these cells and the former is not produced by them in any detectable amount. Fibronectin also increases the attachment of the cells to type IV collagen-coated plates, but laminin lacks this effect. Protein synthesis-blocking agents such as cycloheximide totally abolish the attachment-promoting effect of extracellularly supplied laminin, but not that of extracellular fibronectin. Type IV collagen alone is no better a substratum for these cells than type I collagen or the plastic surface of the dish itself. The importance of an intact tertiary structure for the attachment is obvious in the case of both fibronectin and laminin. Denatured molecules or smaller fragments of these molecules do not promote cell attachment.