Fibronectin from the ovary of the sea urchin,Pseudocentrotus depressus

Fibronectin, with a subunit molecular weight of 220,000 daltons, was isolated from the ovary of the sea urchin,Pseudocentrotus depressus, using affinity chromatography on heat-denatured mammalian collagen coupled to Sepharose 4B. The distribution of fibronectin in the sea urchin ovary was examined by indirect immunofluorescence using antifibronectin serum. The basement membrane and the connective tissues exhibited strong fluorescence. The fibronectin was localized closely together with collagen bundles in the sea urchin ovary. Biochemical and immunological examinations indicate that sea urchin fibronectin has similar properties as those of mammalian fibronectin.