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Structure and evolution of the human genes encoding protein C and coagulation factor IX
Journal of Cellular Biochemistry
|March 1, 1987
Summary
Human protein C and factor IX are homologous, but their genes have different base compositions. The protein C gene may be a more primitive precursor due to distinct gene evolution.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Human protein C is a vitamin K-dependent plasma protein regulating coagulation.
- Protein C degrades cofactors VIIIa and Va, acting as a negative feedback regulator.
- Protein C precursor domains include leader peptide, gla region, EGF segments, and activation peptide/serine protease.
Purpose of the Study:
- To compare the amino acid sequences and gene structures of human protein C and factor IX.
- To investigate the evolutionary relationship between protein C and factor IX genes.
- To explore the reasons behind the differing base compositions of the protein C and factor IX genes.
Main Methods:
- Amino acid sequence comparison between protein C and factor IX.
- Gene structure comparison, focusing on intron positions.
- Analysis of base composition (guanine + cytosine content) of both genes.
Main Results:
- Protein C and factor IX exhibit sequence homology.
- Seven introns in the coding regions of both genes are in identical positions, aligning with domain boundaries.
- Significant difference in base composition: protein C gene is ~60% G+C, while factor IX gene is ~40% G+C.
Conclusions:
- Identical intron positions suggest a common evolutionary origin and gene duplication.
- The differing base compositions may result from extensive deoxycytosine methylation and deamination mutagenesis in the factor IX gene.
- The protein C gene might represent a more ancestral form preceding gene duplication.
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