Organic matrix of the shell of the foraminifer, Heterostegina depressa.

The organic matrix of the benthonic foraminifer, Heterostegina depressa is composed of a heterogeneous assemblage of proteins and polysaccharides. The fraction which is insoluble after decalcification using EDTA is composed almost entirely of over-sulfated glycosaminoglycans. Protein comprises about 0.5% by weight of this fraction. The EDTA-soluble matrix constituents can be separated into different fractions using reversed phase chromatography. Two major classes of matrix macromolecules are present: one containing mainly proteins rich in aspartic acid and the other proteins rich in serine and glycine, possibly linked to polysaccharides. Many of the biochemical properties of the numerous matrix macromolecules present are similar to those of organic matrices from other phyla. -Authors