Contents

18 February 2000
Vol 287, Issue 5456

About The Cover

Cover image expansion

COVER Molecular surface representation of the RNA-protein core of the signal recognition particle (SRP) from the bacterium Escherichia coli. The proposed signal sequence binding groove, highlighted in red against the glassy molecular surface, is made up of protein and RNA, whose backbones are depicted in dark blue. The domain of the SRP is universally conserved (shown in yellow for the RNA), suggesting a common mechanism for signal recognition in all life. See page 1232 [Image: SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE]