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Primary structure of human coagulation factor XIII
1Department of Biochemistry, University of Washington, Seattle 98195.
Insights
Researchers determined the primary structures of human factor XIII
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Human factor XIII is a crucial enzyme in blood coagulation.
- Understanding its subunit structure is vital for comprehending its function.
Purpose of the Study:
- To elucidate the complete primary structures of the alpha (a) and beta (b) subunits of human factor XIII.
- To identify key functional regions within each subunit.
Main Methods:
- Combined cDNA cloning and amino acid sequencing techniques.
- Analysis of amino acid composition and sequence homology.
Main Results:
- The a subunit (731 amino acids) contains an activation peptide, active site, calcium-binding site(s), and thrombin-inactivation site, with functional regions potentially in separate exons.
- The b subunit (641 amino acids) features ten tandem repeats homologous to other proteins, with GP-I structures likely encoded by separate exons.
Conclusions:
- The complete primary structures of human factor XIII's a and b subunits have been determined.
- Structural insights suggest a complex genetic organization and functional compartmentalization within the subunits.
Abstract:
The complete primary structures of the a and b subunits of human factor XIII were determined by a combination of cDNA cloning and amino acid sequencing. The a subunit is composed of 731 amino acids including an activation peptide (37 amino acids), an active site (-Tyr-Gly-Gln-Cys-Glu-), a putative calcium binding site(s), and a thrombin-inactivation site. The functional regions of the a subunit appear to be located in separate exons of its gene. The b subunit consists of 641 amino acids including ten tandem repeats that are homologous with those in at least 13 other proteins. Each GP-I structure in the b subunit is probably encoded by a separate exon.