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.
The structures have two chains, chain A and chain B, marked in green and red, respectively. In the interface, the contact sites on chain A are highlighted in blue, while those on chain B are in magenta. (A)r-l_51; (B)1KU6;(C)r-l_182529.
