Molecular evolution in the hypervariable regions of fetuin: comparison between human and African green monkey fetuin

Area of Science:

• Comparative genomics
• Molecular evolution
• Primate genetics

Background:

• Fetuin, a serum protein, plays roles in various biological processes.
• Understanding evolutionary divergence between species is crucial for biological research.
• Previous studies have not fully elucidated the evolutionary pressures on specific domains of primate fetuin.

Purpose of the Study:

• To compare fetuin cDNA and amino acid sequences between African green monkey (Vero cell line) and humans.
• To investigate the evolutionary pressures acting on different domains of the fetuin protein.
• To analyze the evolutionary rates of other genes (alpha1-antitrypsin, beta-actin) and gene segments (intron 4 of alpha1-antitrypsin) in these species.

Main Methods:

• Sequencing of fetuin cDNA and deduced amino acid residues from Vero cells and human samples.
• Comparative sequence analysis to determine percentage differences.
• Calculation of nonsynonymous and synonymous nucleotide substitution rates.
• Analysis of alpha1-antitrypsin, beta-actin cDNAs, and alpha1-antitrypsin gene intron 4 sequences.

Main Results:

• Fetuin cDNA and amino acid sequences from African green monkey (Vero) differed by 7.3% and 12.9% from human sequences, respectively.
• Amino acid substitutions were concentrated in a small segment of the third domain (D3).
• Calculated substitution rates suggest positive selection acting on the D3 segment.
• Analysis of other genes and gene segments corroborated the findings of positive selection on the D3 segment.

Conclusions:

• The third domain (D3) of fetuin has undergone significant evolutionary changes driven by positive selection in the primate lineage.
• These findings highlight adaptive evolution in a specific functional domain of the fetuin protein.
• Comparative genomic analysis provides insights into the molecular mechanisms of species divergence.