Sulphation of a cell surface glycoprotein from Volvox carteri

Sulphated glycoproteins have been implicated in the control of cell growth and differentiation: fibronectins [ 1,2]; glycoproteins in developing sea urchin embryos [3]; and a surface glycoprotein from V&ox curteri [4]. This V&ox glycoprotein, of 185 000 app. M, [4] appears to be involved in the control of the differentiation of the organism during embryogenesis. Although PAPS or APS must be involved as sulphate donor in the synthesis of such molecules, the incorporation of sulphate from PAPS into a sulphated glycoprotein has been demonstrated only in [5]. It was therefore of interest to partially characterize the sulphate-transfer system operative in Volvos.