Sequence analysis of AC133 antigen. (A) Sequence of AC133 antigen cDNA. The 5-TM domains are underlined, the 8 N-linked glycosylation sites are in boxes (the seventh and eighth glycosylation sites are in 1 larger box; dashed lines indicate where they overlap), and the polyadenylation signal is in a small box. (B) Hydrophobicity analysis of the AC133 antigen protein sequence. The hydrophobic signal peptide is notable along with 5 very hydrophobic TM domains. The last TM domain contains a single lysine in the middle of the TM sequence. (C) Graphic of the proposed structural model of AC133 antigen. This protein is modeled as having an extracellular N-terminus, a cytoplasmic C-terminus (containing 5 tyrosine residues), 2 small cysteine-rich cytoplasmic loops, and 2 very large extracellular loops each containing 4 consensus sequences for N-linked glycosylation. The position of the 4 original peptides is indicated in bold.