Fig. 1: hCD164 structure, epitopes and splice variants.

The hCD164 gene is located on chromosome 6q21, comprises six exons (E1–6) and encodes a type 1 integral transmembrane sialomucin. a hCD164(E1–6) amino acid sequence, with exons (E), glycosylation, mucin domains and motifs. TM transmembrane region. The hCD164(E1–6) isoform with 9 N-linked and 32 O-linked glycans, and a glycosaminoglycan (GAG) attachment site at the end of E5 and beginning of E6. The first mucin domain is encoded by E1, the cysteine rich non-mucin domain by E2 and E3, the second mucin domain by E4 to part of E6, and the transmembrane region, cytoplasmic domain and 3′UTR by the remainder of E6. A cytokine binding pocket is predicted to lie in the non-mucin domain. b Diagrammatic representation of hCD164, indicating regions where the Class I, II, and III hCD164 Mabs bind, and putative intra-molecular disulphide bridges. The molecular mass of the hCD164 monomer or homodimer varies from 80–100 kD to 160–180 kD under respective non-reducing and reducing conditions, while the molecular mass of the GAG modified hCD164 or the hCD164 tetramer exceeds 220 kD. Epitope recognition sites are also shown for representatives of each Class of CD164 Mabs and further elaborated in Fig. 2.