A proteoglycan fraction isolated from the EDTA extract of sea urchin (Hemicentrotus pulcherrimus) gastrulae stimulates reaggregation of dissociated embryonic cells.

A sulfated proteoglycan fraction was prepared from mid-gastrulae Hemicentrotus pulcherrimus by chromatographing the EDTA extract of embryos on DEAE-cellulose and then on Sepharose 6B. A peak fraction (with MW greater than 10(6] of the Sepharose eluates stimulated in a concentration-dependent manner the reaggregation of cells dissociated from Hemicentrotus blastulae by EDTA treatment, the activity being detected at a concentration of as low as 5.8 micrograms protein per ml or 2.5 micrograms fucose per ml. The proteoglycan fraction appeared to contain sulfated fucan and glycosaminoglycan chains linked to a common protein. The glycan moiety obtained by digesting the fraction with protease failed to stimulate the cellular reaggregation.