The properties and regulations of proteins to form cytoskeletons in higher plants

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We have studied about the properties and functions of cytoskeletal elements and its protein compositions in higher plants.Cultured tobacco cells possess minor tubulin-like protein,which is immunologically classified as <alpha>-tubulin. This protein induced the depolymerization and the inhibition of polymerization of microtubules.Immunofluorescent studies using antibodies against tubulin often showed the microtubules protruding from the surface of nuclei to cytoplasm and sometimes to inside of nuclei just like the initiation of spindle microtubules formation.This observation suggested the localization of MTOC-like substances on nuclei.In fact,MTOC-like active substance(s)was prepared from nuclei of higher plants.In vitro polymerizable actin was isolated from hifer plant cells.The biochemical properties would be shown within short time.We found three novel cytoskeletal elements from higher plant cells.They seems to be unique cytoskeletons in higher plants,therefore,the regulation systems … More will be interest.50 kd protein polymerizad intermediate filament-like structures in the presence of guanosine nucleotides.This protein was shown to be basic protein and cross-reacted with antitubulin antibodies.Monoclonal antibodies showed the localization of 50 kd protein around the nuclei and cortical region as network in interphase cells.Phragmoplast was also shown to contain this protein.58 kd protein was purified from insoluble fraction in the presence of ATP,this protein readily solubilized by the depletion of ATP.Addition of ATP induced the reversible polymerization and formed fibrillar bundles of thin filament having a diameter about 3[5 nm.Monoclonal antibodies showed the distribution of this bundles around the surface of nuclei protruding to plasma membrane. Possible involvement of the fibrillar bundles in the mechanism to determine the site at which cytokinesis will occur and to move the nucleus in relation to the division site.100 kd protein was solubilized with KC1 fron insoluble fraction and purified.This protein polymerized double chain filaments haying a diameter about 15 nm in vitro.The function of these cytoskeletal element should be further studied. Less