This is the C-terminal domain found in Bacillus thuringiensis protein Cry35Ab1 (an insecticidal protein). The domain has three helices held in a hydrophobic core, the first two form a typical helix-loop-helix whilst the third helix is perpendicular. The domain is structurally homologous to BinB and proteins containing similar beta-trefoil lectin-like domains. The domain is not required for insecticidal activity or for immuno-reactivity and its function is likely to be to bind to WCR brush border membrane vesicles [1].

1: Structural and biophysical characterization of Bacillus thuringiensis insecticidal proteins Cry34Ab1 and Cry35Ab1. Kelker MS, Berry C, Evans SL, Pai R, McCaskill DG, Wang NX, Russell JC, Baker MD, Yang C, Pflugrath JW, Wade M, Wess TJ, Narva KE; PLoS One. 2014;9:e112555. PMID:25390338