Domain structures of representative zonadhesins and related proteins. Mouse [GenBank: NP035871.1], pig [GenBank: Q28983], human [GenBank: Q9Y493], puffer fish and zebrafish zonadhesins are shown with the salmon and zebrafish Zlg. The human MUC2 [GenBank: L21998.1], human prepro von Willebrand factor [GenBank: P04275] and rat (Rattus norvegicus) MUC2 [GenBank: Q62635] and human and chicken FCGBP proteins [GenBank: NP003881.1 and XP422715.1] are also included. Signal peptide sequences (SP) are drawn as a white box and are found at the N-terminus of all proteins except for puffer fish and zebrafish Zan. All the zonadhesins have an epidermal growth factor (EGF) domain (in red), a transmembrane (TM) domain (in yellow) and a cytoplasmic domain (CD) (in green) which are labeled on the mouse Zan protein. The MAM and mucin domains are indicated and the VWD domains are represented by 'D'. The partial D3 domains of the mouse are represented by D3p1-20. Other partial VWD domains are denoted D0 or D' as found in the current literature. It is important to note that although this domain representation is consistent with previous representations of zonadhesin and other VWD containing proteins, other domain types such as von Willebrand C (VWC) and trypsin inhibitor-like (TILa) domains have not been included here.