This domain is found at the C-terminal end of Isocitrate dehydrogenase [NADP] from Rickettsia typhi and similar bacterial proteins. It is also found in the hypothetical protein TT1725 from Thermus thermophilus HB8. The presence of positively-charged residues in the alpha-1 helix suggests this region binds to a protein with a negatively charged region or to nucleic acids [1].

1: Crystal structure of a hypothetical protein, TT1725, from Thermus thermophilus HB8 at 1.7 A resolution. Seto A, Shirouzu M, Terada T, Murayama K, Kuramitsu S, Yokoyama S; Proteins. 2003;53:768-771. PMID:14579367