The Dictyostelium spore coat is a polarised extracellular matrix composed of glycoproteins and cellulose. Four of the major coat glycoproteins exist as a multi-protein complex within the prespore vesicles before secretion. Of these, SP96 and SP70 are members of this family. The presence of SP96 and SP70 in the complex is necessary for the cellulose binding activity of the complex, which is in turn necessary for normal spore coat assembly. The function of this region of these proteins is not known.