A proteoglycan with affinity for the vegetalizing factor: characterization by density gradient centrifugation

A crude proteoglycan fraction isolated from chicken embryos has an affinity for the vegetalizing factor, which induces mesodermal and endodermal tissues in gastrula ectoderm of Triturus alpestris. Binding of the factor to the crude proteoglycan results in inactivation of the vegetalizing factor. The crude proteoglycan was centrifuged in CsCl and CsCl-urea density gradients. Most of the inactivating material was recovered from the gradients in the high density proteoglycan fraction. Part of the inactivating material was found in glycoproteins of lower density. It is concluded that not all of the polysaccharide moiety of the proteoglycan is involved in binding of the vegetalizing factor. The proteoglycan is inactivated by incubation with hyaluronidase.