Fig. 1.
Hypothetical scenario for the emergence of the MHC, TCR, and BCR molecules by gradual evolution, which encompassed modification of preexisting domains, joining together of different domains, and possibly generation of new domain designs.
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.