Comparative analysis of the soluble organic matrix of axial skeleton and sclerites of Corallium rubrum: Insights for biomineralization

We analysed the soluble organic matrix (SOM) of two biominerals formed by the same organism but differing by their morphological characteristics: the axial skeleton and the sclerites of Corallium rubrum. The results of 1D SDS-PAGE electrophoresis show for the two biominerals that SOM proteins bands have similar apparent molecular weight but differ in quantity. Further analysis by 2D electrophoresis reveals each protein band as a line of spots with different isoelectric points. Our results suggest that each SOM protein band consists of a mix of proteins and/or one unique protein with post-translational modifications. By immunohistochemistry, we show that antibodies raised against the SOM of axial skeleton and sclerites label the SOM of the two biominerals but also label the insoluble organic matrix suggesting the presence of common epitopes between the two biominerals and the two organic fractions.