Complete nucleotide sequence of the gene for human C1 inhibitor with an unusually high density of Alu elements.

The complete (17159 bp) nucleotide sequence of the gene for the human C1 inhibitor has been determined. The transcription initiation site was examined by primer extension using human liver mRNA, and the messenger 5'-end sequence was determined on clones obtained by the anchored polymerase chain reaction. The gene of this serpin molecule is split by seven introns, with junctions of phases zero and one. An outstanding feature of the intron sequences is the occurrence of 17 AluI repeats of all four ancestral subgroups, indicating that the gene has been invaded during consecutive waves of Alu amplification, including a recent one. These Alu repeats form the sites of deletion and insertion in several known lesions in the C1-inhibitor gene. There is no obvious promoter site of the TATA-box type at the 5' end of the gene, but instead it contains a region of potential H-DNA structure similar to that found upstream of the human c-myc gene.