Contents

01 December 1989
Vol 246, Issue 4934

About The Cover

The crystal structure of Escherichia coli glutaminyl-tRNA synthetase (in blue) complexed with tRNAGln (in red and yellow) and adenosine triphosphate (ATP, in green). The structure shows that this enzyme recognizes this specific tRNA and discriminates against the other sixty through extensive interactions with the acceptor stem and anticodon of the tRNA. See pages 1135 and page 1152. [Graphics by M. A. Rould, J. J. Perona, P. Vogt, and T. A. Steitz, Yale University, New Haven, Connecticut]