Organizational types of Asp-box β-propeller proteins. The four organizational types identified from known structures are represented by specific examples. The Asp-boxes are shown as light blue rectangles, Asp-box propeller boundaries are framed in blue, known or predicted blade boundaries are marked by vertical blue lines inside the frame and other domains found in the selected examples are shown as labeled ovals. Type 1 (top); a stretch of Asp-boxes that is not interrupted by any domains forms one β-propeller, shown here is YP299179.1 (3b7f). Type 2 (second from top); a stretch of Asp-boxes is interrupted by an inserted domain, but yet forms a single propeller, shown here is Vibrio Cholera sialidase (1w0p). 'Lect' is a lectin-like domain and 'S-l-ins' represents Pfam: Sial-lect-inser, which is a lectin binding protein-protein interaction domain, which has a fold similar to that of 'Lect'. Type 3 (second from bottom); a stretch of Asp-boxes not interrupted by any domains forms two tandem propellers, shown here is the GH74 protein Avicelase III from Aspergillus aculeatus (BAA29031.1). 'CBM1' stands for carbohydrate binding module 1. Type 4 (bottom); an interrupted stretch of Asp-boxes forms two propellers, shown here is Vps10p from yeast (AAA18831.1). '10CC' represents the two neighboring 10CC-a and 10CC-b domains.
Quistgaard and Thirup BMC Structural Biology 2009 9:46 doi:10.1186/1472-6807-9-46