Book excerpt: Molecular Motors and Muscle is the second of a three-part series on Fibrous Proteins. The books are based on a very successful workshop in Alpbach, Austria on the general topic of Fibrous Proteins that gave rise to the award-winning issue of Journal of Structural Biology. There are two major types of protein: Globular proteins which are often enzymes which speed up biochemical reactions and Fibrous proteins which often have more structural roles but can also have dynamic properties. Fibrous proteins are usually either elongated molecules which pack together to form long filaments, as in the case of the intermediate filaments in our hair and skin and as in collagen fibrils in tendons and bones or they are globular proteins which aggregate linearly to form long filaments, such as actin filaments or microtubules. Fibrous proteins act as molecular scaffolds in cells, they can be involved in transport of cell organelles or even on a visible scale as in our muscles. They provide the supporting structures of our skeletons, bones, tendons, cartilage, and skin. They define the mechanical properties of our internal hollow organs such as the intestines, heart, and blood vessels. They are vital for life and represent a fascinating subset of the proteome. Advances in Protein Chemistry is available online on ScienceDirect - full-text online of volumes 53 onwards. Elsevier book series on ScienceDirect gives multiple users throughout an institution simultaneous online access to an important compliment to primary research. Digital delivery ensures users reliable, 24-hour access to the latest peer-reviewed content. The Elsevier book series are compiled and written by the most highly regarded authors in their fields and are selected from across the globe using Elsevier's extensive researcher network. For more information about the Elsevier Book Series on ScienceDirect Program, please visit: http://www.info.sciencedirect.com/bookseries/ *Allows a comparison to be made between unique but related structures. *Quality of the text and illustrations allows ready comprehension of key protein design features. *Identifies fibrous protein sequence features for analysis of the human genome. *Analyzes design principles for fibrous protein sequences thus leading potentially to development of new devices by nanofabrication.