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.
Each numbered box represents an exon (not drawn to scale). The shorter extensions at the terminal exons represent noncoding DNA. The letters inside the boxes are protein structural features: (S)ecretion peptide, helix (A), helix (B), helix (C) and helix (D).
