Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Comparison of cross-strand A stacks. (A) Superposition of the SRL (green) and the loop E reversed Hoogsteen cross-strand A stacks (12). (B) Tandem-sheared cross-strand A stacks: the P4-P6 domain (10) and the hammerhead ribozyme (11, 31). One of the two observed copies of the P4-P6 domain found in the asymmetric unit does not have an inverted sugar pucker (dashed lines) (10).
