Motor proteins are most closely associated with microtubules and actin filaments, as intermediate filaments are not generally a part of the vesicular transport process. Polymer of proteins -tubulin and -tubulin two major types: axonemal microtubules. Might form permanent part of the cell. Part of structures (axoneme) involved in cell movement. Example: flagella, cilia: cytoplasmic microtubules loosely organized, very dynamic located within the cell in the cytosol, structure. And heterodimers form long protofilaments. Heterodimers aligned in same direction (head to tail: creates polarity. Mts have fast-growing plus end and slow-growing minus end. Structural polarity is important for mt growth/shrinkage and direction of movement of material along mt. 13 protfilaments form a longitudinal array: hollow cylinder hetero = different dimer = two. Mediate interactions with other cellular structures (ex: vesicles organelles) Several different proteins bind mts: non-motor maps. Control microtubule organization in the cytosol neuronal breakdown ie. dementia: motor maps. Associate with and use mictrotubules as tracks.