Identification and genetic mapping of Xenopus TAP2 genes |
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Authors: | Y Ohta S J Powis W John Coadwell Darren E Haliniewski Y Liu Hong Li M F Flajnik |
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Institution: | (1) Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, FL 33101, USA, US;(2) Department of Biochemistry, University of Dundee, Dundee DD1 4HN, Scotland, GB;(3) Department of Immunology, Babraham Institute, Cambridge, UK, GB |
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Abstract: | The amphibian Xenopus laevis is one non-mammalian vertebrate in which the major histocompatibility complex (MHC) has been analyzed extensively. Class
IIβ, class Ia, LMP2, LMP7, HSP70, C4, Factor B, and Ring3 genes have been identified and mapped to the MHC. Here, we report the isolation of a transporter associated with antigen
processing (TAP) gene, TAP2, and demonstrate its linkage to the MHC. While the ATP-binding region of Xenopus
TAP2 is highly conserved in evolution, amino acid identity to other vertebrate TAP proteins was not detected in the N-terminal
region. Segregation analysis of 34 individuals from two families showed exact restriction fragment length polymorphism matching
between the MHC class Ia gene and the one TAP2 gene demonstrating linkage conservation since the mammalian/amphibian divergence ∼350 million years ago. In addition, one
non-MHC-linked TAP2–hybridizing fragment was detected in approximately half of the individuals tested. Interestingly, TAP2 allelic lineages appear to match those of LMP7 and classical class I, which previously were categorized into two highly divergent groups that emerged at least 60 million
years ago. Similar to LMP7 and class Ia,TAP2 is expressed ubiquitously with highest levels in intestine and spleen.
Received: 2 March 1998 / Revised: 15 July 1998 |
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Keywords: | MHC Transporter Evolution PCR cloning Allelic lineage |
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