Evidence for a pool of coronin in mammalian cells that is sensitive to PI 3-kinase

Coronin, a 57 kDa actin binding protein elutes with an apparent molecular m ass of 400-600 kDa from gel filtration columns. This fraction is not unrela ted to the reported 200 kDa complex where coronin is associated with phox p roteins of the NADPH-oxidase. Phosphatidylinositol 3-kinase (PI 3-kinase) s olubilizes coronin from the 400-600 kDa complex, thus constitutive active P I 3-kinase is sufficient to disrupt the complex, whereas wortmannin stabili zes it. Conversely, the phox protein associated pool of coronin is PI 3-kin ase independent. During phagocytosis coronin is recruited together with PI 3-kinase to membranes of nascent and early phagosomes colocalizing with the actin cytoskeleton, confirming that coronin contributes to phagocytosis, ( C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.