Structure of the gene for human von Willebrand factor

Abstract

von Willebrand factor is a large multimeric plasma protein composed of identical subunits which contain four types of repeated domains. von Willebrand factor is essential for normal hemostasis, and deficiency of von Willebrand factor is the most common inherited bleeding disorder of man. Four human genomic DNA cosmid libraries and one bacteriophage lambda library were screened with von Willebrand factor cDNA probes. Twenty positive overlapping clones were characterized that span the entire von Willebrand factor gene. A high-resolution restriction map was constructed for approximately 75% of the locus and a total of approximately 33.8 kilobases was sequenced on both strands including all intron-exon boundaries. The gene is approximately 178 kilobases in length and contains 52 exons. The exons vary from 40 to 1379 base pairs in length, and the introns vary from 97 base pairs to approximately 19.9 kilobases in length. The signal peptide and propeptide (von Willebrand antigen II) of von Willebrand factor are encoded by 17 exons in approximately 80 kilobases of DNA while the mature subunit of von Willebrand factor and 3' noncoding region are encoded by 35 exons in the remaining approximately 100 kilobases of the gene. A number of repetitive sequences were identified including 14 Alu repeats and a approximately 670-base pair TCTA simple repeat in intron 40 that is polymorphic. Regions of the gene that encode homologous domains have similar structures, supporting a model for their origin by gene segment duplication.