Sequence-specific transcription factor (PubMed:29465778). Regulates multiple developmental processes including brainstem, inner and outer ear, abducens nerve and cardiovascular development and morphogenesis as well as cognition and behavior (By similarity). Also part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. Acts on the anterior body structures. Seems to act in the maintenance and/or generation of hindbrain segments (By similarity). Activates transcription in the presence of PBX1A and PKNOX1 (PubMed:29465778). The homeobox domain presumably directs sequence-specific DNA binding. The N-terminal portion of ERA-1-993 may be involved in interactions with one or more other regulatory proteins. Such an interaction could regulate either the DNA-binding activity or the transcriptional regulatory activity of ERA-1-993. The homeoboxless ERA-1-399 protein could act as a competitive inhibitor of the ERA-1-993 protein by competing for interaction with regulatory protein(s) while being unable to bind to DNA. Interacts with OGT (via TPR repeats domain); the interaction takes place mainly in the nucleus (PubMed:29465778). Forms a DNA-binding heterodimer with transcription factor PBX1 (By similarity). Expressed along the entire length of the primitive streak. In early neurogenesis it is expressed in lateral and paraxial mesoderm, endoderm and superficial ectoderm or in the neural tube. From late neurogenesis to mid-embryogenesis, it presents similar spatial domains in the lateral mesoderm, endoderm and superficial ectoderm but is not detectable in any part of the hindbrain. At day 8-8.5 post-coitum found in the embryonic mesoderm, anterior to the first somite, up to the cephalic region at the level of the foregut and developing heart. At day 9 post-coitum found in an anterior part of the developing foregut and is restricted to an epithelial cell type. Expression in the gut is found at the level of the second to third branchial bars. By retinoic acid. Glycosylated by OGT. Belongs to the Antp homeobox family. Labial subfamily.