Pollen tube taxol dependent structures co-assemble with neuronal HMW MAPs (MAP2)

Pollen tube microtubules (MTs) are as dynamic as animal MTs and they may interact with plasma membrane, endoplasmic reticulum, Golgi apparatus, mitocondria and a variety of cytoplasmic proteins. Bridges connecting MTs to each other and to membranes have been documented in pollen tubes by electron microscopy; however, the biochemical and molecular nature of these linkages is not known. In other cell types interaction between organelles and MTs require the participation of Microtubule-Associated Proteins (MAPs) that bridge the cytoskeleton to these organelles. Although biochemical documentation of such bridging MAPs in plant cells is lacking, it is reasonable to assume, by analogy with the animal systems, that specialized MAPs regulate MTs polymerization and dynamic in pollen tube. As a first step toward testing this hypothesis, the ability of Nicotiana tabacum pollen tube taxol-stabilized MTs to bind mammalian brain High Molecular Weight MAPs (HMWMAPs)(MAP2) was tested. This association analysis revealed the presence of mammalian MAP2-binding sites on pollen tube taxol-induced structures suggesting that the association presumably occurs at conserved domains on the tubulin molecules