PROGRESS IN Nucleic Acid Research and Molecular Biology edited by WALDO E. COHN KlVlE MOLDAVE Biology Division Oak Ridge National Laboratory Oak Ridge, Tennessee Departmnt of Molecular Biology and Biochemistry University of California, Zroine lrvine, California Volume 57 ACADEMIC PRESS Son Diego New York Boston London Sydney Tokyo Toronto This book is printed on acid-free paper. Copyright 0 1995 by ACADEMIC PRESS, INC. All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Academic Press, Inc. A Division of Harcourt Brace & Company 525 B Street, Suite 1900, San Diego, California 92101-4495 United Kingdom Edition published by Academic Press Limited 24-28 Oval Road, London NW 1 7DX International Standard Serial Number: 0079-6603 International Standard Book Number: 0- 12-540051-9 PRINTED IN THE UNITED STATES OF AMERICA 95 96 9 7 9 8 99 0 0 B B 9 8 7 6 5 4 3 2 1 Abbreviations and Symbols All contributors to this Series are asked to use the terminology (abbreviations and symbols) recommended by the IUPAC-IUB Commission on Biochemical Nomenclature (CBN) and approved by IUPAC and IUB, and the Editors endeavor to assure conformity. These Recommendations have been published in many journals ( 1 , 2 )and compendia (3);they are therefore considered to be generally known. Those used in nucleic acid work, originally set out in section 5 of the first Recommendations (I)and subsequently revised and expanded (2, 3), are given in condensed form in the frontmatter of Volumes 9-33 of this series. A recent expansion of the oneletter system (5) follows. SINGLE-LETTER CODERECOMMENDATIONS~(5) Symbol Meaning Origin of symbol Guanosine Adenosine (ribo)Thymidine (Uridine) Cytidine R Y M K S Wb G or A T(U) or C A or C G or T(U) G or C A or T(U) puRine pyrimidine aMino Keto Strong interaction (3 H-bonds) Weak interaction (2 H-bonds) H B V DC A or C or T(U) G or T(U) or C C or C or A G or A or T(U) not not not not N G or A or T(U) or C aNy nucleoside (i.e., unspecified) Q Q Queuosine (nucleoside of queuine) 6 ;H follows G in the alphabet A; B follows A T (not U); V follows U C; D follows C .Modified from Proc. Natl. Acad. Sci. U.S.A. 83, 4 (1986). bW has been used for wyosine, the nucleoside of “base Y” (wye). CDhas been used for dihydrouridine (hU or H,Urd). Enzymes In naming enzymes, the 1984 recommendations of the IUB Commission on Biochemical Nomenclature ( 4 ) are followed as far as possible. At first mention, each enzyme is described either by its systematic name or by the equation for the reaction catalyzed or by the recommended trivial name, followed by its EC number in parentheses. Thereafter, a trivial name may be used. Enzyme names are not to be abbreviated except when the substrate has an approved abbreviation (e.g., ATPase, but not LDH, i s