Appearance of a proteoglycan in developing sea urchin embryos.

It was shown that a proteoglycan is synthesised by embryos of a Japanese sea urchin, Hemicentrotus pulcherrimus. This proteoglycan appears as a single peak on sucrose density gradient ultracentrifugation throughout the development. About half of the mucopolysaccharide moiety in this proteoglycan was found to be dermatan sulphate and the rest to be chondroitinase-resistant mucopolysaccharides. Evidence is presented to show that both types of mucopolysaccharide do not exist in a free form but reside as an integral part of the proteoglycan. The linkage between mucopolysaccharide and protein moieties of the proteoglycan appeared not to be an O-glycosidic bond, which is common among other proteoglycans such as proteochondroitin sulphate and proteodermatan sulphate.