Entactin forms a complex with fibronectin and co-localizes in the extracellular matrix of the embryonal carcinoma-derived 4CQ cell line.

A novel extracellular matrix that consists of a complex of fibronectin and entactin was synthesized by the embryonal carcinoma-derived cell line 4CQ. The matrix was devoid of laminin. High steady state levels of the messenger RNAs for fibronectin, entactin, and the B2 chain of laminin were detected in these cells. Laminin B1 message was several fold lower while laminin A chain message was undetectable. In contrast, in the sister embryonal carcinoma-derived cell M1536-B3 there were high levels of message for all three chains of laminin and for entactin but very little for fibronectin. The data suggest that the synthesis and deposition of laminin and fibronectin are inversely related. The direct binding of entactin and fibronectin was also demonstrated by affinity column chromatography and solid phase assay.