This is a family of bacterial glycoside hydrolases formerly known as cellulase family J, and now known as Cel44A. It is one of the major enzymatic components of the cellulosome of Clostridium thermocellum strain F1 and of many other Firmicutes.

1: Crystal structure of Cel44A, a glycoside hydrolase family 44 endoglucanase from Clostridium thermocellum. Kitago Y, Karita S, Watanabe N, Kamiya M, Aizawa T, Sakka K, Tanaka I; J Biol Chem. 2007;282:35703-35711. PMID:17905739

2: Structure and activity of Paenibacillus polymyxa xyloglucanase from glycoside hydrolase family 44. Ariza A, Eklof JM, Spadiut O, Offen WA, Roberts SM, Besenmatter W, Friis EP, Skjot M, Wilson KS, Brumer H, Davies G; J Biol Chem. 2011;286:33890-33900. PMID:21795708