and efficient sliding movements of microtubules. Another branch is cytoplasmic dyneins which facilitate the transport of intracellular cargos. Compared to 15 types of axonemal dynein, only two cytoplasmic forms are known. Genomic representation of dynein motors: Fungi (yeast): 1 Plants (Arabidopsis thaliana): 0 Insects (Drosophila melanogaster): 13 Mammals (human): 14-15 Plant-specific motors In contrast to animals, fungi and non-vascular plants, the cells of flowering plants lack dynein motors. However, they contain a larger number of different kinesins. Many of these plant-specific kinesin groups are specialized for functions during plant cell mitosis. Plant cells differ from animal cells in that they have a cell wall. During mitosis, the new cell wall is built by the formation of a cell plate starting in the center of the cell. This process is facilitated by a phragmoplast, a microtubule array unique to plant cell mitosis. The building of cell plate and ultimately the new cell wall requires kinesin-like motor proteins. Another motor protein essential for plant cell division is kinesin-like calmodulin-binding protein (KCBP), which is unique to plants and part kinesin and part myosin. Other molecular motors Besides the motor proteins above, there are many more types of proteins capable of generating forces and torque in the cell. Many of these molecular motors are ubiquitous in both prokaryotic and eukaryotic cells, although some, such as those involved with cytoskeletal elements or chromatin, are unique to eukaryotes. The motor protein prestin, expressed in mammalian cochlear outer hair cells, produces mechanical amplification in the cochlea. It is a direct voltage-to-force converter, which operates at the microsecond rate and possesses piezoelectric properties. See also ATP synthase Cytoskeleton Protein dynamics References External links MBInfo - What are Motor Proteins? Ron Vale's Seminar: "Molecular Motor Proteins" Biology of Motor Proteins Institute for Biophysical Chemistry, Göttingen Jonathan Howard (2001), Mechanics of motor proteins and the cytoskeleton. Cell movement Molecular machines