A predicted alpha+beta domain that is usually fused N-terminal to the JAB metallopeptidase. This protein in turn is found in conserved gene neighborhoods that include genes encoding the bacterial homologs of the ubiquitin modification system such as the E1, E2 and Ub proteins [1]. The domain is also known as the JAB-N domain.

1: The prokaryotic antecedents of the ubiquitin-signaling system and the early evolution of ubiquitin-like beta-grasp domains. Iyer LM, Burroughs AM, Aravind L; Genome Biol. 2006;7:R60. PMID:16859499