Isolation and characterization of the human inter‐α‐trypsin inhibitor heavy‐chain H1 gene

Abstract

The human inter-a-trypsin inhibitor heavy chain HI (IT1 heavy chain H1) gene was isolated from two overlapping clones. It spans 14 kbp and is composed of 22 exons from 15 bp to 281 bp in size and has consensus splice sites. Intron sizes range from 80 bp to 2000 bp. It codes for the precursor of HCI that is part of the serum IT1 form of 220 kDa. Two major transcriptional initiation sites were identified in the 5'-flanking region, which contained putative promoter elements, but no typical TATA and CAAT boxes. mRNA for the IT1 heavy chain H1 was found only in liver. The tissue-specific transcription of the gene might be due to the presence of binding sites for the hepatocyte nuclear factor HNF-5 and to the octameric motifs. A previous overlapping of cDNA clones indicated the absence of 29 bp in one of these clones. The present study shows that the 29 bp is located within the gene at the end of exon 21. A reverse-transcriptase polymerase chain reaction mapping analysis of liver mRNA identified the two types of the mRNA for IT1 heavy chain H1. Accordingly, the data demonstrate that there is alternative splicing of at least one exon of the IT1 heavy chain H1 gene.The human inter-a-trypsin inhibitor (ITI) heavy-chain H1 and H3 genes are located exclusively in the p21.1-21.2 region of chromosome 3 [l]. The IT1 family members are plasma serine proteinase inhibitors in mammals (reviewed in [2]). We have described the four chains that are implicated in this family, i.e. three heavy chains (HI, H2, H3) and one light chain (L) [l]. The four genes of the IT1 family are mapped to three differents chromosomes 111. Actually, the IT1 family is composed of at least four members: the IT1 itself, a 220-kDa glycoprotein made of H1, H2 and bikunin chains; the pre-a-trypsin inhibitor (PaI), composed of H3 and bikunin chains; an uncomplexed bikunin molecule, and a 130-kDa trypsin inhibitor molecule made of H2 and bikunin chains [3]. The chains are linked by a glycosaminoglycan chain [3-51. Only the structure of the human light-chain gene has been established so far. Separate exons of the L precursor code for two proteins, a,-microglobulin and bikunin, that have no typical functional feature [6, 71. The ex-

Human Inter-α-Trypsin Inhibitor Heavy Chain H3 Gene

“…6 plaques of a human genomic (leukocyte) library (CLONTECH) constructed in EMBL3 were screened by plaque hybridization with full-length ITI heavy chain cDNA probes labeled with 32 P by the random primer method. Hybridization was carried out as described by Maniatis et al (36).…”

“…31). The ITIH1 gene spans 14 kb and is composed of 22 exons (32). The ITIH4 * This work was supported by Association pour la Recherche sur le Cancer.…”

ITIH1*Q0 iwate, a null allele of inter-alpha-trypsin inhibitor H1 caused by deletion/frameshift mutation

“…The ITIHI chain is composed of 877 amino acid residues with a molecular mass of 92 kDa (Diarra-Mehrpour et al, 1992). The ITIHI gene spans about 14 kb and includes 22 exons with 15-281 bp in size (Bost et al, 1993). Three common alleles, ITIHI* 1, ITIHI*2 and ITIHI*3, are characterized by amino acid substitutions at positions 551 and 561 in exon 14 (Ding et al, 1995a).…”

“…Oligonucleotide primer pairs for the amplification of 22 exons were designed from genomic sequence of ITIH1 gene (Bost et al, 1993) as shown in Table 1. Each exon was amplified by PCR mostly according to Thiberville et al (1994).…”

“…In this study, 22 pairs of primers were prepared to analyze every coding exons of ITIH1 gene. Some of primers contained nucleotide sequences of coding regions (Table 1), because of the limited genomic sequence data (Bost et al, 1993). Only a few short regions of coding exons and a Y-flanking region were not analyzed.…”