Abstract
In this work, to study the emergence of the H chain V region repertoire during mammalian evolution, we present an analysis of 25 independent H chain V regions from a monotreme, the Australian duck-billed platypus, Ornithorhynchus anatinus. All the sequences analyzed were found to form a single branch within the clan III of mammalian V region sequences in a distance tree. However, compared with a classical V gene family this branch was more diversified in sequence. Sequence analysis indicates that the apparent lack of diversity in germline V segments is well compensated for by relatively long and highly diversified D and N nucleotides. In addition, extensive sequence variation was observed in the framework region 3. Furthermore, at least five and possibly seven different J segments seem to be actively used in recombination. Interestingly, internal cysteine bridges in the complementarity-determining region (CDR)3 loop, or between the CDR2 and CDR3 loops, are found in approximately 36% of the platypus V(H) sequences. Such cysteine bridges have also been observed in cow, camel, and shark. Internal cysteine bridges may play a role in stabilizing long and diversified CDR3 and thereby have a role in increasing the affinity of the Ab-Ag interaction.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Antibody Diversity* / genetics
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Base Sequence
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Cattle
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Cloning, Molecular
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Complementarity Determining Regions / analysis
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Complementarity Determining Regions / genetics
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DNA, Complementary / analysis
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Germ-Line Mutation / immunology*
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Immunoglobulin Heavy Chains / analysis*
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Immunoglobulin Heavy Chains / genetics
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Immunoglobulin Variable Region / analysis*
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Immunoglobulin Variable Region / genetics
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Molecular Sequence Data
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Multigene Family / immunology
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Platypus / genetics
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Platypus / immunology*
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Sequence Alignment / methods
Substances
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Complementarity Determining Regions
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DNA, Complementary
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Immunoglobulin Heavy Chains
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Immunoglobulin Variable Region
Associated data
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GENBANK/AF381289
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GENBANK/AF381290
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GENBANK/AF381291
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GENBANK/AF381292
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GENBANK/AF381293
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GENBANK/AF381294
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GENBANK/AF381295
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GENBANK/AF381296
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GENBANK/AF381297
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GENBANK/AF381298
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GENBANK/AF381299
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GENBANK/AF381300
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GENBANK/AF381301
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GENBANK/AF381302
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GENBANK/AF381303
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GENBANK/AF381304
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GENBANK/AF381305
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GENBANK/AF381306
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GENBANK/AF381307
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GENBANK/AF381308
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GENBANK/AF381309
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GENBANK/AF381310
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GENBANK/AF381311
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GENBANK/AF381312
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GENBANK/AF381313
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GENBANK/AF381314
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GENBANK/AF381315
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GENBANK/AF381316
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GENBANK/AF381317
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GENBANK/AF381318
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GENBANK/AF381319
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GENBANK/AF381320
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GENBANK/AF381321
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GENBANK/AF381322
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GENBANK/AF381323
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GENBANK/AF381324