About CETN / Centrin:
Centrin is a type of protein that is essential for practically all eukaryotic cells. Also called caltractin by some researchers, these proteins are mainly found in the centrosome, particularly the centrioles and the pericentriolar lattice. In humans, CETN1, CETN2 and CETN3 genes code the protein. The molecular weight of the protein is 20 kDa.
Centrin was first isolated and discovered in 1984 in the flagellar roots of green algae. Researchers found that it was essential in calcium channel metabolism. The protein appeared to have a high affinity for calcium and a much lower affinity for phosphorus and other mineral constituents of the cell.
The function of centrin is to facilitate the duplication of centrioles and severing of microtubules by calcium-mediated contraction. However, a lot of the centrin within cells is non-centrosomal, found in high concentrations outside of the centrosome. The function of this extra-centrosomal material is not yet fully understood by researchers.
Experiments using chemical crosslinking have found that centrin has a particular affinity for actin and the N-terminal portion of the HC. However, further immunoprecipitation assays are required to confirm this
Centrin is part of the EF-hand superfamily of calcium-binding proteins. It contains four helix-loop-helix features specially designed for binding with calcium in certain parts of the cell. Centrin can be found in the transitional region of the axoneme, the bridge between the nucleus and the basal body, and both the proximal and distal fibres connecting the two basal bodies. It is also present in a set of fibres that connect the number 7 and 8 microtubule blades.