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Immunogenetics

, Volume 56, Issue 9, pp 631–638 | Cite as

Genomic analysis reveals a duplication of eight rather than seven short consensus repeats in primate CR1 and CR1L: evidence for an additional set shared between CR1 and CR2

  • C A McLure
  • J F Williamson
  • B J Stewart
  • P J Keating
  • R L Dawkins
Original Paper

Abstract

We report the discovery of previously unrecognised short consensus repeats (SCRs) within human and chimpanzee CR1 and CR1L. Analysis of available genomic, protein and expression databases suggests that these are actually genomic remnants of SCRs previously reported in other complement control proteins (CCPs). Comparison with the nucleotide motifs of the 11 defined subfamilies of SCRs justifies the designation g-like because of the close similarity to the g subfamily found in CR2 and MCP.

To date, we have identified five such SCRs in human and chimpanzee CR1, one in human and chimpanzee CR1L, but none in either rat or mouse Crry in keeping with the number of internal duplications of the long homologous repeat (LHR) found in CR1 and CR1L. In fact, at the genomic level, the ancestral LHR must have contained eight SCRs rather than seven as previously thought. Since g-like SCRs are found immediately downstream of d SCRs, we suggest that there must have been a functional dg set which has been retained by CR2 and MCP but which is degenerate in CR1 or CR1L. Interestingly, dg is also present in the CR2 component of mouse CR1. The degeneration of the g SCR must have occurred prior to the formation of primate CR1L and prior to the duplication events which resulted in primate CR1. In this context, the apparent conservation of g-like SCRs may be surprising and may suggest the existence of mechanisms unrelated to protein coding.

These results provide examples of the many processes which have contributed to the evolution of the extensive repertoire of CCPs.

Keywords

Complement control proteins Short consensus repeats CR1 CR1-L Evolution Duplication Degeneracy 

Notes

Acknowledgements

The authors gratefully acknowledge the support of the Immunogenetics Research Foundation, Genetic Technologies, the National Health and Medical Research Council of Australia, the Australian Research Council and Equitech. C.M. is supported by an APA scholarship

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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • C A McLure
    • 1
    • 2
  • J F Williamson
    • 1
    • 2
  • B J Stewart
    • 1
    • 2
  • P J Keating
    • 2
  • R L Dawkins
    • 1
    • 2
    • 3
  1. 1.Centre for Molecular Immunology and InstrumentationUniversity of Western AustraliaNedlandsAustralia
  2. 2.Canning ValeAustralia
  3. 3.Centre for Molecular Immunology and InstrumentationUniversity of Western AustraliaCanning Vale SouthAustralia

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