Coronin

Coronin is an actin binding protein which also interacts with microtubules and in some cell types is associated with phagocytosis. Coronin proteins are expressed in a large number of eukaryotic organisms from yeast to humans.

Discovery

Initially, a 55 kDa protein was isolated from the actomyosin complex of Dictyostelium discoideum, which was later shown to bind actin in vitro. This actin binding protein was named coronin after its strong immunolocalisation in the actin rich crown like extension of the cell cortex in D. discoideum. Initially this protein was admitted into club of actin binding proteins with least enthusiasm, as the primary structure did not match any other ABPs. But null mutation of coronin in D. discoideum resulted in impaired cytokinesis, and many actin mediated processes like endocytosis, cell motility etc. Later on, the protein was identified in many eukaryotic cells.

Structure

Coronin belongs to the WD-repeat containing proteins, which form a beta propeller tertiary structure. The crystal structure of coronin 1A (see figure to the right) containing major part of the protein was solved in 2006.