Figure 5From: Animal Ca2+ release-activated Ca2+ (CRAC) channels appear to be homologous to and derived from the ubiquitous cation diffusion facilitatorsProposed Common Origin for CRAC channels and CDF carriers. The figure illustrates two potential pathways: the likely pathway whereby triplication of the primordial hairpin structure gave rise to a 6 TMS CDF carrier, followed by loss of TMSs 1-2 to give 4 TMS Orai channels. See text for details.Back to article page