9.B.55 The 4 TMS DUF307/YccF (DUF307) Family 

This family includes the E. coli YccF 4 TMS protein of unknown function.  This domain contains two 2 TMSs repeated in tandem. This 2 TMS domain is found in some calcium:cation antiporters of the CaCA family.  These proteins have TC#s 2.A.19.7.1 &2.