Caspartin and Calprismin, Two Protiens of the Shell Calcitic Prsims of the Mediterranean Fan Mussle Pinna nobilis

Frédéric Marin et al JBC 2005

Two proteins were isolated one is 38-kDA (calprismin) another one is  17kDA(caspartin). Caspartin forms mutlimers and self-aggregates and inhibits the precipitation of calcium carbonate precipitation in vitro. Caspartin is found between the prsims and the surrounding insoluble sheets, this suggests the prominent role of aspartic acid-rich proteins for the building of calcitic prsims among mollusks.

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Role of water-soluble matrix fraction, extracted from the nacre of Pincatada maxima, in the regulation of cell activity in abalone mantle cell culture (Halioitis tuberculata)

D.Sud, D. Doumenc, E. Lopez, C. Milet

In the Abalone Haloits tuberculata, they have established a cell culture of the mantle tissue, they used MTT to assess the viablility of cells,  they used the water soluble extract of the organic matrix, on the cell culture, the WSM reduced the viability of cells, but yet increased the activity of alkaline phosphatase. Hemocytes and eptithelial cells are known to cooperate with mantle cells in shell regeneration and in pearl production (awaji & Suziki 1995). It appears that the WSM of P.maxima controls, mantle cell activity.

Dentin Sialophosphoprotein (DSPP) in Biomineralization

Two of the proteins found in significant quantity in the extracellular matrix (ECM) of dentin are dentin phosphoprotein (DPP) and dentin sialoprotein (DSP). DPP, the most abundant of the non-collagenous proteins in dentin is an unusually polyanionic protein, containing a large number of aspartic acids (Asp) and phosphoserines (Pse) in the repeating sequences of (Asp-Pse)n. and (Asp-Pse-Pse)n. The many negatively charged regions of DPP are thought to promote mineralization by binding calcium and presenting it to collagen fibers at the mineralization front during the formation of dentin. This purported role of DPP is supported by a sizeable pool of in vitro mineralization data showing that DPP is an important initiator and modulator for the formation and growth of hydroxyapatite crystals. Quite differently, DSP is a glycoprotein, with little or no phosphate. DPP and DSP are the cleavage products of dentin sialophosphoprotein (DSPP). Human and mouse genetic studies have demonstrated that mutations in, or knockout of, the Dspp gene result in mineralization defects in dentin and/or bone. The discoveries in the past 40 years with regard to DPP, DSP and DSPP have greatly enhanced our understanding of biomineralization and set a new stage for future studies. In this review, we summarize the important and new developments made in the past four decades regarding the structure and regulation of the DSPP gene, the biochemical characteristics of DSPP, DPP and DSP, as well as the cell/tissue localizations and functions of these molecules.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2933432/

Of course, we know what is coming next right? 😉