A technique for detecting matrix proteins in the crystalline spicule of the sea urchin embryo

Jin Won Cho, Jacqueline S. Partin, William J. Lennarz

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21 Citations (Scopus)

Abstract

The presence of proteins associated with the CaCO3-containing biocrystals found in a wide variety of marine organisms is well established. In these organisms, including the primitive skeleton (spicule) of the sea urchin embryo, the structural and functional role of these proteins either in the biomineralization process or in control of the structural features of the biocrystals is unclear. Recently, one of the matrix proteins of the sea urchin spicule, SM 30, has been shown to contain a carbohydrate chain (the 1223 epitope) thai has been implicated in the process whereby Ca2+ is deposited as CaCO3. Because an understanding of the localization of this protein, as well as other proteins found within the spicule, is central to understanding their function, we undertook to develop methods to localize spicule matrix proteins in intact spicules, using immunogold techniques and scanning electron microscopy. Gold particles indicative of this matrix glycoprotein could not be detected on the surface of spicules that had been isolated from embryo homogenates and treated with alkaline hypochlorite to remove any associated membranous material. However, when isolated spicules were etched for 2 min with dilute acetic acid (10 mM) to expose more internal regions of the crystal, SM 30 and perhaps other proteins bearing the 1223 carbohydrate epitope were detected in the calcite matrix. These results, indicating that these two antigens are widely distributed in the spicule, suggest that this technique should be applicable to any matrix protein for which antibodies are available.

Original languageEnglish
Pages (from-to)1282-1286
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume93
Issue number3
DOIs
Publication statusPublished - 1996 Feb 6

All Science Journal Classification (ASJC) codes

  • General

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