Arylsulfatase exists as non-enzymatic cell surface protein in sea urchin embryos

The physiological role of arylsulfatase (Ars) and its function during development have yet to be satisfactorily defined in any species, though the proteins are widely distributed and the genes have been cloned from various organisms. Here we report the dual location of two types of Ars in sea urchin embryos. The majority of sea urchin Ars does not exhibit enzyme activity and is extracellularly distributed in aboral ectoderm cells (nonenzymatic Ars). Only a small portion has enzyme activity and is localized in lysosomal vesicles (enzymatic Ars). The elution pattern of Ars proteins processed by DEAE-cellulose or analytical gel-column chromatography reveals that although the molecular radius of enzymatic Ars differs from that of nonenzymatic Ars, they have the same charge. Furthermore, sedimentation analysis shows that purified Ars of sea urchin embryos is soluble in the absence of divalent cations but becomes insoluble in the presence of Ca2+ or Mg2+. Taken together, the present results suggest that non-enzymatic Ars is a new member of the cell surface component or extracellular matrix. It is possible that this cell surface Ars plays an important role in morphogenesis of sea urchin embryos.