This domain is found at the N-terminus of eubacterial magnesium transporters of the MgtE family Pfam:PF01769. This domain is an intracellular domain that has an alpha-helical structure. The crystal structure of the MgtE transporter [1] shows two of 5 magnesium ions are in the interface between the N domain and the CBS domains. In the absence of magnesium there is a large shift between the N and CBS domains.

1: Crystal structure of the MgtE Mg2+ transporter. Hattori M, Tanaka Y, Fukai S, Ishitani R, Nureki O; Nature. 2007;448:1072-1075. PMID:17700703