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Characterization of two mannose-binding protein cDNAs from rhesus monkey (Macaca mulatta): structure and evolutionary
1Department of Pathology, Boston University School of Medicine, MA 02118, USA.
Glycobiology
|July 1, 1996
Summary
Primate evolution of mannose-binding proteins (MBPs) reveals two forms in monkeys but only one in chimpanzees and humans. This suggests a gene loss in the hominoid lineage, impacting innate immunity.
Area of Science:
- Immunology
- Evolutionary Biology
- Molecular Genetics
Background:
- Mannose-binding proteins (MBPs), part of the collectin family, function as lectin opsonins, crucial for innate immunity against pathogens.
- Rodents possess two distinct MBP forms (MBP-A and MBP-C), while only one human MBP form has been identified.
- Understanding primate MBP evolution is key to deciphering variations in innate immune responses.
Purpose of the Study:
- To investigate the evolutionary history and genetic diversity of mannose-binding proteins (MBPs) in primates.
- To compare MBP forms in different primate species and relate findings to human and rodent MBP structures.
- To elucidate the evolutionary pressures and potential gene loss events affecting MBP diversity in the hominoid lineage.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) and Western blot analysis were used to detect MBP forms in serum samples from rhesus and cynomolgus monkeys, and chimpanzees.
- Two distinct MBP cDNA clones were isolated and characterized from a rhesus monkey liver cDNA library.
- Phylogenetic analysis was performed on rhesus and other mammalian MBP sequences.
Main Results:
- Rhesus and cynomolgus monkeys possess two MBP forms in their sera, whereas chimpanzees, like humans, have only one.
- Rhesus MBP-A shows high amino acid identity to rodent MBP-A and shares key structural features, including N-terminal cysteines.
- Rhesus MBP-C is highly similar to human MBP and possesses three N-terminal cysteines, differing from rodent MBP-C.
Conclusions:
- Phylogenetic and serological data suggest that at least two distinct MBP genes predated mammalian radiation.
- The hominoid ancestor likely lost or ceased expression of one MBP gene, leading to the single MBP form observed in humans and chimpanzees.
- This evolutionary event may have implications for the diversity of innate immune recognition in higher primates.