Cellular proteolytic systems, volume 15. Edited by Aaron J. Ciechanover and Alan L. Schwartz. Modern Cell Biology Series. New York: John Wiley and Sons. (1994). 233 pp. $84.95

To classical biochemists, enzymologists, or cell biologists, proteolysis has been a problem that could wreak havoc with weeks of meticulous work when they find a particular activity is "dead" as a result of proteolytic degradation. Indeed, it may not be entirely coincidental that several proteases have the syllables "pain" in their names. In the past decade, proteases have assumed new respectability owing to the recognition that controlled proteolysis regulates many cellular processes, including quality control in the endoplasmic reticulum (ER); virus assembly; the biosynthesis of peptide hormones, neuropeptides, and hormone receptors; polypeptide hormone turnover; anti-gen processing; stages in embryonic development; and tumorigenicity. Schwartz, is Volume 15 in the Modern Cell Biology series published by Wiley-Liss. Rather than describing the characteristics and biochemical properties of cellular prote-ases, the book attempts to integrate proteolytic degradation in the context of cell biology by describing protein turnover in various organelles and systems. The strength of the book is that the range of topics will make it of interest to many different investigators. However, a number of important recent developments in which selective proteolytic cleavage has been shown to play an essential role are not well covered. For example, processing of peptide hormone and neuropeptide precursors by prohormone con-vertases, the yeast (Saccharomyces cerevisiae) Kex2 pro-tease that cleaves pro-R-factor to mature R-mating factor, and furin, the mammalian homolog of the Kex2 protease, which is implicated in the cleavage of several viral envelope glycoprotein precursors, warrant a separate chapter. The cursory treatment given them in the book is unfortunate because in the past 5 years these enzymes have been an intense area of research (for a review of this area, see Steiner et al., 1992). Ubiquitin, one of the most highly conserved proteins known, is a 76 amino acid polypeptide that, when conjugated to cellular proteins, targets them for degradation. Despite considerable effort, relatively few natural sub-strates that are ubiquitinylated in vivo have been identified. Part of the initial chapter by the book's editors is devoted to examples of proteins that undergo ubiquitin-mediated proteolysis, including the p53 tumor suppressor, the c-myc and c-myb proto-oncogenes, and cyclins. Together, the first two chapters present a comprehensive review of the ubiquitin-mediated degradation pathway. This includes the enzymology of ubiquitin-conjugating enzymes, which have also been implicated in cell cycle progression (UBC3) and peroxisome biogenesis (UBC10). The chapter also includes a good discussion of the ATP-dependent 26S protease complex or proteasome and …