The ribonuclease A superfamily of mammals and birds: Identifying new members and tracing evolutionary histories

Soochin Cho, Jaap J. Beintema, Jianzhi Zhang

Research output: Contribution to journalArticlepeer-review

145 Scopus citations


The RNase A superfamily has been important in biochemical, structural, and evolutionary studies and is believed to be the sole vertebrate-specific enzyme family. To understand the origin and diversification of the superfamily, we here determine its entire repertoire in the sequenced genomes of human, mouse, rat, and chicken. We report a previously unnoticed gene cluster in mouse chromosome 10 and a number of new genes, including mammalian RNases 11-13, which are close relatives of the recently identified RNases 9 and 10. Gene expression data imply male-reproductive functions for RNases 9-13, although their sequences suggest the lack of ribonucleolytic activities. In contrast to the presence of 13-20 functional genes in mammals, chicken has only 3 RNase genes, which are evolutionarily close to mammalian RNase 5, like other nonmammalian RNases. This and other evidence suggests that the RNase A superfamily originated from an RNase 5-like gene and expanded in mammals. Together with the fact that multiple lineages of the superfamily, including RNases 2, 3, 5, and 7, have antipathogenic activities, we suggest that the superfamily started off as a host-defense mechanism in vertebrates. Consistent with this hypothesis, all members of the superfamily exhibit high rates of amino acid substitution as is commonly observed in immunity genes.

Original languageEnglish (US)
Pages (from-to)208-220
Number of pages13
Issue number2
StatePublished - Feb 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics


Dive into the research topics of 'The ribonuclease A superfamily of mammals and birds: Identifying new members and tracing evolutionary histories'. Together they form a unique fingerprint.

Cite this