Centrins, also known as caltractins, are a family of calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

-binding phosphoprotein

Phosphoprotein

Phosphoproteins are proteins that are physically bonded to a substance containing phosphoric acid . This category of organic molecules includes Fc receptors, Ulks, Calcineurins, K chips, and urocortins....

s found in the centrosome

Centrosome

In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center of the animal cell as well as a regulator of cell-cycle progression. It was discovered by Edouard Van Beneden in 1883...

 of eukaryote

Eukaryote

A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

s. Centrins are present in the centriole

Centriole

A Centriole is a barrel-shaped cell structure found in most animal eukaryotic cells, though it is absent in higher plants and most fungi. The walls of each centriole are usually composed of nine triplets of microtubules...

s and pericentriolar lattice. Human centrin genes are CETN1

CETN1

Centrin-1 is a protein that in humans is encoded by the CETN1 gene. It belongs to the centrin family of proteins.-Further reading:...

, CETN2

CETN2

Centrin-2 is a protein that in humans is encoded by the CETN2 gene. It belongs to the centrin family of proteins.-Interactions:CETN2 has been shown to interact with XPC.-Further reading:...

 and CETN3

CETN3

Centrin-3 is a protein that in humans is encoded by the CETN3 gene. It belongs to the centrin family of proteins.-Further reading:...

.

Function

Centrins are required for duplication of centrioles. They may also play a role in severing of microtubule

Microtubule

Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...

s by causing calcium-mediated contraction. The majority of centrin in the cell is non-centrosomal whose function is not yet clear.

Structure

Centrin belongs to the EF-hand superfamily of calcium-binding proteins and has four calcium-binding EF-hands. It has a molecular weight of 20 kDa.