Organization of the human alpha 2-plasmin inhibitor gene.

Hirosawa, Shinsaku; Nakamura, Yūichi; Miura, Osamu; Sumi, Yôichi; Aoki, Nobuo

doi:10.1073/pnas.85.18.6836

Cited by 51 publications

(38 citation statements)

References 42 publications

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“…10,[36][37][38][39][40] The gene contains 10 exons and 9 introns and spans approximately 16 kb of DNA. 41 The complete complementary DNA sequence shows 23% to 28% homology with other members of the serpin family and 73% to 81% homology with a2AP from other species, such as rat, mouse, cow, and rabbit. 42,43 Exon 1 of the human SERPINF2 gene consists entirely of untranslated sequences.…”

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“…The amino terminal (N-terminal) region of the protein comprising the glutamine involved in crosslinking to fibrin is encoded by exon 4, whereas both the RCL containing the reactive site arginine and the plasminogen-binding site in the C-terminal region are encoded by exon 10. 41 An alternatively spliced isoform of a2AP has been reported that lacks exon 5 (NM_001165921), although the expressed amount of this variant or any consequences of its function have not yet been described.Native a2AP molecules contain 11% to 14% carbohydrate (four putative N-linked glycosylation sites at asparagine residues 99, 268, 282, and 289) and a sulfated tyrosine residue at position 457.44 This leads to a molecular weight of approximately 67 000. 10,14,36 Furthermore, a2AP contains 1 disulfide bridge (between the cysteine residues in positions 43 and 116) that does not appear to have a profound influence on the structure or function of a2AP.…”

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Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

Abdul

Leebeek

Rijken

et al. 2016

Blood

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Human a2-antiplasmin (a2AP, also called a2-plasmin inhibitor) is the main physiological inhibitor of the fibrinolytic enzyme plasmin. a2AP inhibits plasmin on the fibrin clot or in the circulation by forming plasmin-antiplasmin complexes. Severely reduced a2AP levels in hereditary a2AP deficiency may lead to bleeding symptoms, whereas increased a2AP levels have been associated with increased thrombotic risk. a2AP is a very heterogeneous protein. In the circulation, a2AP undergoes both amino terminal (N-terminal) and carboxyl terminal (C-terminal) proteolytic modifications that significantly modify its activities. About 70% of a2AP is cleaved at the N terminus by antiplasmin-cleaving enzyme (or soluble fibroblast activation protein), resulting in a 12-amino-acid residue shorter form. The glutamine residue that serves as a substrate for activated factor XIII becomes more efficient after removal of the N terminus, leading to faster crosslinking of a2AP to fibrin and consequently prolonged clot lysis. In approximately 35% of circulating a2AP, the C terminus is absent. This C terminus contains the binding site for plasmin(ogen), the key component necessary for the rapid and efficient inhibitory mechanism of a2AP. Without its C terminus, a2AP can no longer bind to the lysine binding sites of plasmin(ogen) and is only a kinetically slow plasmin inhibitor. Thus, proteolytic modifications of the N and C termini of a2AP constitute major regulatory mechanisms for the inhibitory function of the protein and may therefore have clinical consequences. This review presents recent findings regarding the main aspects of the natural heterogeneity of a2AP with particular focus on the functional and possible clinical implications. (Blood. 2016; 127(5):538-545) Introduction a2-antiplasmin (a2AP, also called a2-plasmin inhibitor) is a key player in the fibrinolytic system (Figure 1). The fibrinolytic system is crucial for dissolving fibrin clots, facilitating tissue repair, and preventing clots from occluding vessels.1 Recent clinical studies have shown that reduced fibrinolysis (eg, due to an increase in a2AP level) is associated with an increase in both venous and arterial thrombotic risk. 2In contrast, an increase in fibrinolysis due to a2AP deficiency is associated with hemophilia-like bleeding symptoms, which typically occur after initial hemostasis as a result of the premature dissolution of fibrin. The phenotype of a2AP deficiency is heterogeneous. Complete congenital a2AP deficiency leads to severe bleeding with hemophilialike bleeding symptoms such as joint bleeding, whereas heterozygous a2AP-deficient patients typically have mild or no bleeding symptoms. 3,4 In addition, acquired a2AP deficiency may also occur in liver disease 5 and amyloidosis 6 or during fibrinolytic therapy. 7The main enzyme of the fibrinolytic system is the serine protease plasmin, which is predominantly responsible for the degradation of fibrin into rapidly cleared soluble fibrin degradation products (Figure 1). The inactive proenzyme plasminogen ca...

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Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

Abdul

Leebeek

Rijken

et al. 2016

Blood

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“…Agarose gel electrophoresis, transfer to nitrocellulose filters, hybridization, washing of filters and autoradiography were carried out by standard procedures (18). For use as probes, a 750 base pair (bp) Eco RI/Hind III fragment of the human a2PI cDNA clone pPI39 (11), coding for the carboxyl-terminal half of a2PI, and an 890 bp Pst I fragment of the human genomic a2PI clone XPI6 (15), containing exons II, III, and IV, were labeled with a_-[32P]dCTP by nick translation.…”

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confidence: 99%

“…However, nothing was known about the molecular basis for the patients with congenital a2PI deficiency with no detectable circulating antigen. Since we have isolated and characterized the human a2PI gene (15), it has now become possible to analyze the gene from these patients with a2PI deficiency. Therefore, this study was undertaken to elucidate the molecular basis for a pedigree of hereditary a2PI deficiency by analyzing the a2PI gene from an individual homozygous for this trait (16).…”

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Molecular basis for congenital deficiency of alpha 2-plasmin inhibitor. A frameshift mutation leading to elongation of the deduced amino acid sequence.

Miura

Hirosawa²,

Kato³

et al. 1989

J. Clin. Invest.

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The present study was designed to elucidate the molecular genetic basis of a familial deficiency of a2-plasmin inhibitor (a2PI)-Southern blot hybridization analysis with human a2PI cDNA and genomic DNA probes demonstrated no gross deletion or rearrangement of the gene. By sequencing all the coding exons and exon-intron boundaries of the gene of a homozygote, we identified a single cytidine nucleotide insertion in the exon coding for the carboxyl-terminal region. This frameshift mutation leads to an alteration and elongation of the carboxyl-terminal portion of the deduced amino acid sequence. Synthetic oligonucleotide probes confirmed this frameshift mutation in all the affected family members including both heterozygous parents. In a transient expression assay, the a2PI level in the culture medium of the cells transfected with the mutated a2PI expression vector was very low and only 4% of that of the cells transfected with the normal vector, although the transcript levels and the cellular contents of a2PIs did not differ significantly. Elongation of amino acid sequence in the mutant a2PI was confirmed by an analysis of a2PI in a transient expression experiment. These data indicate that this mutation is the cause of a2PI deficiency in this pedigree.

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