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\"This book provides an easy-to-read, user-friendly resource for industrial chemists and a text for classroom use, and is an unparalleled tool for understanding and applying the latest information on surfactants. Problems are included at the end of each chapter to enhance the reader's understanding, along with many tables of data that are not compiled elsewhere. Only the minimum mathematics is used in the explanation of topics to make it easy-to-understand and very user friendly\"-- Source other than Library of Congress.

Protein degradation by the ubiquitin-proteasome system is essential to maintain cellular homeostasis. The recognition, unfolding, and degradation of aberrant proteins is accomplished by the proteasome. Eukaryotic 26S proteasomes are composed of multiple individual subunits that assemble in a specific order to form a functional complex consisting of a 20S core particle (CP) and a 19S regulatory particle (RP). Yeast CP is composed of seven different a and seven different β subunits that assemble into four stacked rings, with two α-subunit rings sandwiching a pair of inner β-subunit rings. Assembly of the CP is aided by several dedicated chaperones, such as the proteasome biogenesis-associated (Pba) factors Pba1-Pba2 and Pba3-Pba4. Data presented in this dissertation show that the Saccharomyces cerevisiae Pba1-Pba2 heterodimer associates specifically with an immature 20S proteasome intermediate. This interaction occurs via conserved HbYX (hydrophobic-tyrosine-any amino acid) motifs present at the Pba1 and Pba2 C-termini, which contact the outer α-ring surface of the CP. Interestingly, archaea possess a related HbYX-containing protein, PbaA, that also interacts specifically with an immature CP assembly intermediate. The interaction of Pba1-Pba2 with the immature CP suggests allosteric communication between the β active sites and the outer surface of the α ring. Another chaperone complex studied in this dissertation is Pba3-Pba4, which is necessary for the fidelity of α-ring assembly. Yeast missing this factor form α rings that place an additional α4 subunit in place of the α3 subunit. Cells that harbor proteasomes with this alternative α-ring arrangement resist oxidative stress. Attenuation of proteasome function by several distinct means confers such resistance, which is dependent on two transcription factors, Rpn4 and Yap1. Simply reducing proteasome subunit levels is sufficient for oxidative stress resistance. Proteasomes from resistant strains also have proteasome assembly defects correlated with a decrease in Pba3-Pba4 levels. This suggests that mild proteotoxic stress confers cross-protection against severe oxidative stress. In summary, this work demonstrates how Pba1-Pba2 interacts with the proteasome and uncovers a functional role for Pba3-Pba4. That mildly attenuated proteasome activity confers resistance against oxidative stress further suggests that proteasome assembly might be regulated for this purpose. This work has yielded a better understanding of the assembly pathway of the eukaryotic 20S proteasome and opened new avenues of research into its regulation.