This domain is hemagglutinin I (HA1) present in Physarum polycephalum. Although the physiological function of the secreted HA1 remains to be established, HA1 recognizes cell wall polysaccharides of E. coli. The beta-sandwich fold of HA1, composed of two up and down beta-sheets, is conserved among other legume lectin-like proteins. The up and down beta-sheet region is a minimal carbohydrate recognition domain [1].

1: The Structure of Physarum polycephalum hemagglutinin I suggests a minimal carbohydrate recognition domain of legume lectin fold. Kouno T, Watanabe N, Sakai N, Nakamura T, Nabeshima Y, Morita M, Mizuguchi M, Aizawa T, Demura M, Imanaka T, Tanaka I, Kawano K; J Mol Biol. 2011;405:560-569. PMID:21094650