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Description (résumé)

To construct their skeletons, all metazoans secrete a complex array of macromolecules that are supposed to display key-functions in biomineralization, such as crystal nucleation and crystal growth orientation. These macromolecules - generally less than 1% of the skeletal weight - are occluded during skeletal growth and can be retrieved and analyzed by dissolving the mineral phase. They comprise proteins, glycoproteins, peptides, polysaccharides, and sometimes, lipids, pigments and metabolites. They constitute collectively the 'calcifying matrix', from which proteins and glycoproteins are the most studied.  In the last decade, the coupling of high-throughput screening techniques (transcriptomics + proteomics) has allowed the identification of a large number of proteins of the "skeletal repertoires", in diverse metazoan phyla. To give an idea, in mollusks, more than 1000 proteins are now listed as putative shell proteins, in about 30 different genera. Proteomic data underline the diversity of these proteins, which goes along with the diversity of functions required for calcifying a skeleton. Beside expected members (acidic proteins, proteins with hydrophobic domains), shell proteomes (aka 'shellomes') reveal a large variety of proteins with very different low complexity domains. Above all, the surprise comes from the discovery of a huge set of proteins involved in immunity and defense mechanisms in general. This last aspect will be particularly discussed in my talk.

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• Biochimie (572)

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