This domain is found at the C-terminal end of Minor structural protein 5 from Lactococcus phage Tuc2009 (BppU) and similar proteins from tailed bacteriophages and prophages found mostly in firmicutes. BppU is a viral baseplate component. This domain folds into a structure formed mostly by beta-strands [1].

1: The Atomic Structure of the Phage Tuc2009 Baseplate Tripod Suggests that Host Recognition Involves Two Different Carbohydrate Binding Modules. Legrand P, Collins B, Blangy S, Murphy J, Spinelli S, Gutierrez C, Richet N, Kellenberger C, Desmyter A, Mahony J, van Sinderen D, Cambillau C; mBio. 2016;7:e01781-e01715. PMID:26814179