These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Isolation of the Xenopus complement factor B complementary DNA and linkage of the gene to the frog MHC.
    Author: Kato Y, Salter-Cid L, Flajnik MF, Kasahara M, Namikawa C, Sasaki M, Nonaka M.
    Journal: J Immunol; 1994 Nov 15; 153(10):4546-54. PubMed ID: 7963526.
    Abstract:
    C factor B (Bf) is the key component of the C3 convertase of the alternative C pathway, and its gene resides in the class III region of the mammalian MHC. To elucidate the evolution of both the C system and the MHC, we isolated Bf cDNA clones from Xenopus laevis, an ectothermic vertebrate in which the MHC has been well defined at both the biochemical and functional levels. A part of the serine protease domain of the Xenopus Bf mRNA was amplified by reverse transcriptase-PCR, using degenerate primers corresponding to regions encoding the perfectly conserved amino acid sequences found in both the mouse Bf and C2 proteins. A full length Xenopus Bf cDNA clone was isolated from a Xenopus liver cDNA library. The deduced amino acid sequence of 747 residues showed the same domain structure as mammalian Bf and C2: three short consensus repeat domains, a von Willebrand domain and a serine protease domain. Xenopus Bf has 40% and 30% overall amino acid identity to mouse Bf and mouse C2, respectively. Because the amino acid identity between mouse Bf and mouse C2 is 38%, the gene duplication of Bf/C2 probably occurred before the divergence of amphibians and mammals. Southern blotting analysis of the Xenopus Bf gene showed a close linkage to the MHC, indicating that the Bf gene was linked to the class I and class II genes at the time Xenopus shared a common ancestor with mouse and man, 350 x 10(6) yr ago.
    [Abstract] [Full Text] [Related] [New Search]