Globotriaosyl ceramide (Gb3 or CD77) is a glycolipid cell surface recognition receptor for Shiga toxin molecules. Shiga toxins are a family of related bacterial toxins that bind to globotriaosylceramide on various human cell types including germinal center stage B cells, endothelial cells and certain cells of the nervous system. The Gb3 binding site found in Shiga toxin may help provide important clues to elucidate the functions of Gb3 in mammalian cells. Shiga toxin-like amino acid sequences have been found on the human interferon-alpha receptor protein IFNAR-1 and on the B cell protein CD19. Bioinformatics techniques including BLAST searches and the use of Cn3D to visualize protein structures were used to analyze and annotate additional mammalian proteins with sequences similar to the Gb3-binding region of the Shiga toxin B-subunit.The single letter amino acid sequence of the Shiga toxin B-subunit was used in this research to identify potential proteins that could provide information regarding the role of Gb3 in a variety of cell functions including interferon signaling and cell adhesion pathways. A number of protein structures with potential Gb3-binding sites identified by the Blast searches were examined using Cn3D and evaluated for similarities to the Gb3-binding site 3 of Shiga toxins.
