The heterotrimeric Elba complex is required for chromatin domain boundary function during early embryogenesis. It binds to a 8-bp sequence 5'-CCAATAAG-3' in the Fab-7 insulator or boundary element in the bithorax complex and contributes to its insulator or boundary activity. Elba3 lacks DNA-binding activity and plays the role of an adapter protein, bringing Elba1 and 2 together, thereby establishing a complex that recognizes the asymmetric sequence motif through the BEN domains of Elba1 and 2 (PubMed:23240086). The heterotrimeric Elba complex consists of Bsg25A/Elba1, Elba2 and Elba3. Expression is developmentally restricted, peaks at the blastoderm stage (2-4 hours) and then disappears (at protein level).