This volume contains the proceedings of the 45th Mosbach Colloquium of the German Society for Biological Chemistry (GBCh). The 1994 meeting was the first in this series devoted to the cytoskeleton. This complex system enables the eukaryotic cell to form discrete contacts with neighboring cells and the extracellular matrix, to differentiate, to move, change shape, transport organelles, and proliferate. These diverse tasks are performed by three distinct fibrillar networks: microfilaments, microtubules, and intermediate filaments, which are composed of structural and regulatory elements. The precise interplay between the components in time and space determines which of the various functions is performed. The rapid progress made in this field is best exemplified by the recent unraveling of the molecular mechanism of intracellular movement. Here, the modem microscopies of today allow the motility to be visualized in realtime. Molecular biology has dissected the functional domains of the motor proteins involved and provided material required for biochemical studies as well as structure analysis by X-ray diffraction and NMR. Thus, it is now possible to integrate cellular behavior and molecular structure in a unifying picture. Other recent advances in the field point to the role of cytoskeletol proteins in human diseases, from allergies to skin blistering, atrophies, and Alzheimers's disease. The book is an up-to-date account of the field told by an international set of experts, a broad introduction to newcomers, and a valuable reference for practitioners. January 1995 Brigitte M.