Figure 4-30. Recognition of a tRNA by aminoacyl synthetases. Aspartyl-tRNA synthetase (AspRS) is a class II enzyme, and arginyl-tRNA synthetase (ArgRS) is a class I enzyme.

Figure 4-30Recognition of a tRNA by aminoacyl synthetases. Aspartyl-tRNA synthetase (AspRS) is a class II enzyme, and arginyl-tRNA synthetase (ArgRS) is a class I enzyme

Shown here are the outlines of the three-dimensional structures of the two synthetases. The tRNA shown between them as a ribbon diagram will bind to either and is a slightly modified version of tRNAAsp. It is used as an illustration of common surface interactions between tRNA and class I and II enzymes. Sites on the opposite sides of this modified tRNAAsp make contacts with the two enzymes: the blue balls show contacts with the class II AspRS; those that make contact with class I ArgRS are indicated by yellow balls. The synthetases are shown positioned away from the tRNA for clarity, but the fit of the surfaces at close range is obvious. The ability of ArgRS to interact with the noncognate tRNAAsp is lost when residue G37 in tRNAAsp is methylated, a normal modification that occurs in vivo. However, the shape and binding sites of this modified tRNA are characteristic of class I and class II interactions with tRNAs. This molecular graphic picture was produced using the DRAWNA program. [Adapted from M. Sissler et al., 1997, Nucl. Acids Res. 25:4899; courtesy of R. Giegé.]

From: Section 4.4, The Three Roles of RNA in Protein Synthesis

Cover of Molecular Cell Biology
Molecular Cell Biology. 4th edition.
Lodish H, Berk A, Zipursky SL, et al.
New York: W. H. Freeman; 2000.
Copyright © 2000, W. H. Freeman and Company.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.