Gene expression, translation and the behavior of proteins / edited by David M. Prescott, Lester Goldstein.

Date:
1980
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Gene expression, translation and the behavior of proteins / edited by David M. Prescott, Lester Goldstein. Source: Wellcome Collection.

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    1. The Translational Machinery 5 and RajBhandary, 1976). Primary structures have been reported for more than 100 dififerent tRNA's obtained from a variety of organisms ranging from bacteria to mammals (Gauss et al., 1979). A large number of recent detailed reviews on tRNA chemistry and structure are available (Rich and RajBhandary, 1976; Clark, 1977; Ofengand, 1977; Rich, 1978). An outline of the basic structures and principles is given below. Transfer RNA's are not random coils of single-stranded RNA, but are folded into active globular conformations which can be denatured. All of the known tRNA sequences may be organized conceptually into a planar secondary structure which resembles a cloverleaf pattern. The cloverleaf, as shown in Fig. lA for yeast tRNA^^^, is composed of a stem and three arms; each arm consists of a stem and loop. Stems are antiparallel double-strained helical regions, while loops are non-base-paired regions. Comparison of different tRNAs indicates that the cloverleaf structure has both constant and variable features (see Fig. IB). The following gener¬ alizations apply to nearly all known tRNA's. Aqh с D arm G A D G Gg A cue I I I GAG A m2G I C, mj G С A pG—С С—G G—С G—и A—и и—A u- U acceptor stem Т arm G A .1 I m=C и С I G С и и т ^ m'A G С m'C С—G С—G А—и G А—»/' Cm А и Y Gm А А m^G variable loop anticodort arm В. I с I Ç 5'-end „ ? po—о о—о I I 0 — о 1 о он 3 - end acceptor stem о I I 9—9 ^ о—9 T arm D arm I .Pu-A o- U I Pu' o-o-o 6....A' ß o-o-Py-o •O-C I Py- Pu o-o-o-o p-O-Pu' • G ([ variable loop >—o^^o... I I о—о I I о—о о—о anticodon arm Py о I Pu 0-0-0 arìticodon Fig. 1. The secondary structure of tRNA. (A) Yeast tRNA''*. The nucleotide sequence is organized into the planar cloverleaf pattern typical of all tRNA's. Symbols used for modified nucleosides are Ч', pseudouridine; T, ribothymidine; Y, modified purine; D, dihydrouridine; m, methylated bases. (B) Constant and variable features of tRNA. Nucleotide residues are shown by circles except for invariant bases, which are identified by letters. Regions with variable numbers of nucleotides are shown by dotted lines and are discussed in the text. Symbols used are Py, pyrimidine; Pu, purine; Ч', pseudouridine; T, ribothymidine. Adapted from Rich (1978).
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