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Isolation of frog and chicken cDNAs encoding heparin cofactor II
1Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Thrombosis and Haemostasis
|December 8, 1998
Summary
Heparin cofactor II (HCII), a thrombin inhibitor, is present in frogs and chickens, not just mammals. This suggests a conserved role for HCII across diverse vertebrate species.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Heparin cofactor II (HCII) is a serpin that inhibits thrombin, with activity found in human, rabbit, and mouse plasma.
- Previous isolation of HCII cDNA clones from mammalian liver libraries suggested a conserved physiological role.
Purpose of the Study:
- To investigate the presence and characteristics of HCII in non-mammalian vertebrates.
- To determine the evolutionary conservation of HCII across different vertebrate classes.
Main Methods:
- Screening of frog and chicken liver cDNA libraries using a human HCII cDNA probe.
- Analysis of amino acid sequences deduced from cloned cDNAs.
- Detection of dermatan sulfate-dependent inhibitor activity in frog and chicken plasma forming a complex with thrombin.
Main Results:
- Frog and chicken plasma contain a dermatan sulfate-dependent inhibitor that forms an 118-kDa complex with thrombin.
- Nearly full-length HCII cDNA clones were isolated from frog (1.8 kb) and chicken (1.7 kb) liver libraries.
- Deduced amino acid sequences showed approximately 60% identity between frog and chicken HCII, and with mammalian sequences, with conserved functional domains.
Conclusions:
- Heparin cofactor II (HCII) is widely distributed among vertebrates, including birds and amphibians.
- The conserved structure suggests a common, fundamental function for HCII across these diverse species.
