Poster: Cytoskeleton: Structure & Function
Abs #
1105: Studies on molecular mechanism of cytoplasmic streaming:characterization of an actin-bundling protein, p-115-ABP
|
|
Presenter: |
Shimmen, Teruo , shimmen@sci.himeji-tech.ac.jp |
Authors | Shimmen, Teruo (A) Orii, Hidefumi (A) Yokota, Etsuo (A) | | Affiliations: |
(A): Department of Life Science, Graduate School of Science, Himeji Institute of Technology
|
|
|
We are aiming at elucidation of molecular mechanism of cytoplasmic streaming. We have isolated myosin from germinating pollen of Lilium longiflorum. This was the first success in isolating plant myosin which showed sliding movement along actin filament (Yokota and Shimmen 1994). Thus, one of our targets is myosin motor involved in cytoplasmic streaming. To further understand cytoplasmic streaming, mechanism for organization of actin filament, a track for myosin motor, must be studied. We have succeeded in isolating two actin-bundling proteins from germinating pollen of L. longiflorum , one composed of 135 kDa polypeptide (P-135-ABP, Yokota et al. 1998) and the other composed of 115 kDa polypeptide (p-115-ABP, Nakayasu et al. 1998). The target of the present study is P-115-ABP. P-115-ABP shared similar antigenicity with P-135-ABP, a plant homologue of villin. The P-115-ABP isolated biochemicaly from the germinating lily pollen was able to arrange actin filaments with uniform polarity into bundles and this bundling activity was suppressed by calcium-calmodulin , similar to P-135-ABP. The P-115-ABP type of plant villin was widely distributed in plant cells, from algae to land plants. In root hair cells of Hydrocharis dubia , this type plant villin was co-localized with bundles of actin filaments in the transvacuolar strands and the sub-cortical regions. Microinjection of the antiserum against P-115-ABP into living root hair cells caused the disappearance of transvacuolar strands. In internodal cells of Chara corallina in which the P-135-ABP type of plant villin is lacking, the P-115-ABP type showed co-localization with actin-filament cables anchored on the inner surface of chloroplast.
