This family is found in proteins thought to be involved in the response to hypoxia. Family members mostly come from diverse eukaryotic organisms however eubacterial members have been identified. This region is found at the N-terminus of the member proteins which are predicted to be transmembrane [1].

1: Hypoxia-induced gene expression profiling in the euryoxic fish Gillichthys mirabilis. Gracey AY, Troll JV, Somero GN; Proc Natl Acad Sci U S A 2001;98:1993-1998. PMID:11172064