Effects of the dinucleotide deletion on the secondary structure of GPIbα. (A) DNA sequence analysis of GPIbα from a normal individual (bottom) and the patient (top). Nucleotides 2059 and 2060 are deleted in the patient; deleted nucleotides are shown with an arrow. (B) Alignment of the transmembrane region (doubly underlined) of the wild-type GPIbα and the mutant protein (GPIbαΔAT). The start of the alternate reading frame resulting from the AT deletion in the mutant coding sequence is shown in bold type. The charged amino acids following the transmembrane region are shown with a +. (C) Hydropathy plot using the method of Kyte and Doolittle39 performed on the transmembrane and surrounding amino acids of the wild-type GPIbα and GPIbαΔAT. The hydropathy plot for the mutant protein is shown as a broken line.