LOCALIZATION OF KINESIN IN MATURE SIEVE TUBES OF APIUM-GRAVEOLENS

Kinesin, a kind of microtubule-dependent motor proteins responsible fo r active transport in animal cells, is identified and localized in mat ure sieve tubes of Apium graveolens, especially on sieve plates. On We stern blot of phloem proteins, anti-kinesin antibodies specifically re cognize the protein band with ATPase( adenosine triphosphatase) activi ty. Confocal laser scanning micrographs show that the anti-kinesin ant ibodies yield some fluorescent spots and filamentous structures in mat ure sieve tubes, Especially label a layer of structure on sieve plate, and make the plate look like having a cap on it but with some fluores cent labeling anchored into the sieve pores. The kinesin is presumed t o function as active ''pump'' for the long-distance transport of organ ic substances of phleom.