Cortexillins, major determinants of cell shape and size, are actin-bundling proteins with a parallel coiled-coil tail

Article Abstract:

Dictyostelium discoideum has two cortexillins that are necessary for cell shape maintenance and for regular cytokinesis. Cortexillins I and II of Dictyostelium discoideum differ from the known members of the alpha-actinin/spectrin superfamily because of the presence of a two-stranded coiled-coil tail domain by which two subunits are assembled in a parallel and unstaggered way. The actin-binding sites of the subunits are brought in juxtaposition, which makes possible the cross-linking of actin filaments into bundles. Cortexillins were named as such because they are usually found in the highly motile Dictyostelium cell's cortical region, where actin filaments form high order, variably shaped structures.

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Coronin involved in phagocytosis: dynamics of particle-induced relocalization visualized by a green fluorescent protein tag

Article Abstract:

The coronin protein of Dictyostelium discoideum controls phagocytosis of yeast particles. Coronin joined to a green fluorescent protein accumulates in the phagocytotic cups formed after a particle attaches to the cell surface. Coronin is released after the particle is engulfed. The rate of phagocytosis decreases in mutants which lack coronin. Coronin also controls the speed of locomotion. The protein changes signals generated by different activities into cytoskeletal processes. Phagocytosis occurs by a zipper mechanism and is dynamically controlled.

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The role of tricorn protease and its aminopeptidase-interacting factors in cellular protein degradation

Article Abstract:

Tricorn protease is known to be the primary enzyme of a modular proteolytic system with multicatalytic activity. The mode of cooperation between Tricorn and its interacting factors were examined and two additional factors, F2 and F3, were identified. In relation to these three factors, Tricorn breaks down oligopeptides in a sequential fashion, producing free amino acids. A proteolytic pathway composed of the proteasome, Tricorn, and its interacting factors, F1, F2 and F3, were reconstituted.

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