SSR4 is a member of the TRAP-delta family. SSR4 is the delta subunit of the translocon-associated protein complex that participates in translocating proteins through the endoplasmic reticulum membrane. SSR4 positioned in the Xq28 region and organized in a compact head-to-head manner with the isocitrate dehydrogenase 3 (NAD+) gamma gene. Both genes are motivated by a CpG-embedded bidirectional promoter.