Roles of phosphorylation of ERM proteins and ERM-binding membrane proteins in cellular morphogenesis

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1 : Effects of overexpression of ERM-binding membrane proteins (CD43, CD44 and ICAM-2) on microvilli formationOverexpression of these membrane proteins in L and CV1 cells resulted in elongation of microvilli, indicating these proteins are major components of microvilli together with ERM proteins.2 : Localization of ERM proteins phosphorylated at the COOH-terminal threonine residue (CPERMs)We developed new fixation protocol using trichloroacetic acid as a fixative to determine precise localization of CPERMs. They were localized just beneath the plasma membrane of microvilli, reflecting that CPERMs are activated ERM proteins as membrane-cytoskeleton cross-linkers.3 : ERM protein activation in cellular morphogenesisUse of Rho inhibitor, C3, protein kinase inhibitor, staurosporine, and PIP2 inhibitor, neomycin revealed that importance of Rho activity and phosphorylation of ERM proteins depends on cell type. However PIP2 was found to be essential without exception for activation of ERM proteins as well as microvilli formation.