ABSTRACT
IV. THE TARGET PROTEINS 66 A. Elongation Factor 2 (EF-2) 66 B. G Proteins 67 C. Ras, Rho, and the Small GTP-Binding Proteins 68 D. Actin 68
V. THE ACTIVE SITE: A COMMON STRUCTURE AND ACTIVITY 70 A. Primary Structure Homology 70 B. Tertiary Structure Homology 70 C. The ADP-Ribosylation Reaction 72
REFERENCES 74
ADP-ribosylation is a mechanism widely used in nature to modify the properties of proteins and modulate their function. The prokaryotic enzymes that are known to have ADP-ribosylating activity are reported in Table 1. In bacteria, most of the proteins with ADP-ribosylating activity are toxins that have profound effects on eukaryotic organisms and are often the primary cause of severe diseases. For this reason, bacterial toxins with ADP-ribosylating activity have been widely studied and are the best-known
Bacterial ADP-Ribosyltransferases 61
ADP-ribosylating proteins. However, a great deal of evidence is being accumulated on many enzymes that control crucial pathways of eukaryotic cells through ADP-ribosylation. In this chapter we focus mainly on bacterial toxins with ADP-ribosylating activity. Since each of these toxins is separately described in this book, in this chapter we concentrate on the features that are common to this family of toxins and point out the common properties that underlie their activity.
