RRC ID 29033
Author Müller-Taubenberger A, Lupas AN, Li H, Ecke M, Simmeth E, Gerisch G.
Title Calreticulin and calnexin in the endoplasmic reticulum are important for phagocytosis.
Journal EMBO J.
Abstract Calreticulin and calnexin are Ca2+-binding proteins with chaperone activity in the endoplasmic reticulum. These proteins have been eliminated by gene replacement in Dictyostelium, the only microorganism known to harbor both proteins; family members in Dictyostelium are located at the base of phylogenetic trees. A dramatic decline in the rate of phagocytosis was observed in double mutants lacking calreticulin and calnexin, whereas only mild changes occurred in single mutants. Dictyostelium cells are professional phagocytes, capable of internalizing particles by a sequence of activities: adhesion of the particle to the cell surface, actin-dependent outgrowth of a phagocytic cup, and separation of the phagosome from the plasma membrane. In the double-null mutants, particles still adhered to the cell surface, but the outgrowth of phagocytic cups was compromised. Green fluorescent protein-tagged calreticulin and calnexin, expressed in wild-type cells, revealed a direct link of the endoplasmic reticulum to the phagocytic cup enclosing a particle, such that the Ca2+ storage capacity of calreticulin and calnexin might directly modulate activities of the actin system during particle uptake.
Volume 20(23)
Pages 6772-82
Published 2001-12-3
DOI 10.1093/emboj/20.23.6772
PMID 11726513
PMC PMC125758
MeSH Animals Animals, Genetically Modified Blotting, Southern Calcium / metabolism Calcium-Binding Proteins / metabolism Calcium-Binding Proteins / physiology* Calnexin Calreticulin Cell Adhesion Chemotaxis DNA, Complementary / metabolism Dictyostelium Endoplasmic Reticulum / metabolism* Genetic Vectors Green Fluorescent Proteins Luminescent Proteins / metabolism Mice Mice, Inbred BALB C Microscopy, Fluorescence Models, Genetic Mutation Phagocytosis Phylogeny Protein Binding Protein Structure, Tertiary Recombinant Fusion Proteins / metabolism Ribonucleoproteins / metabolism Ribonucleoproteins / physiology* Time Factors Transformation, Genetic
IF 10.557
Times Cited 126
Cellular slime molds S00474 S00475 S90291