This Methods in Enzymology volume continues the description (initiated in Volume 85) of the purification and assay of this diverse group of proteins involved in cytoplasmic organization. It discusses some of the more promising attempts to apply techniques of molecular biology genetics and molecular cytochemistry to these proteins. The critically acclaimed laboratory standard for more than forty years, Methods in Enzymology is one of the most highly respected publications in the field of biochemistry. Since 1955, each volume has been eagerly awaited, frequently consulted, and praised by researchers and reviewers alike. Now with more than 300 volumes (all of them still in print), the series contains much material still relevant today--truly an essential publication for researchers in all fields of life sciences.