This domain is the non-catalytic carbohydrate binding module 77 (CBM77) present in Ruminococcus flavefaciens. CBMs fulfil a critical targeting function in plant cell wall depolymerisation. In CBM77, a cluster of conserved basic residues (Lys1092, Lys1107 and Lys1162) confer calcium-independent recognition of homogalacturonan [1].

1: Complexity of the Ruminococcus flavefaciens cellulosome reflects an expansion in glycan recognition. Venditto I, Luis AS, Rydahl M, Schuckel J, Fernandes VO, Vidal-Melgosa S, Bule P, Goyal A, Pires VM, Dourado CG, Ferreira LM, Coutinho PM, Henrissat B, Knox JP, Basle A, Najmudin S, Gilbert HJ, Willats WG, Fontes CM; Proc Natl Acad Sci U S A. 2016;113:7136-7141. PMID:27298375