1995 Fiscal Year Final Research Report Summary
Structural analysis of the human immunoglobulin H-chain locus
| Project/Area Number |
06670349
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Immunology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
MATSUDA Fumihiko Kyoto University, Center for Molecular Biology and Genetics, Assistant Professor, 遺伝子実験施設, 助手 (50212220)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Immunoglobulin gene / Physical map / Multigene family / YAC / Nucleotide sequence / Translocation / Gene conversion |
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| Research Abstract |
The human immunoglobulin V_H region genes are clustered at the distal end of chromosome 14 (14q32.33). The human V_H segments are classified into 7 families and members of different families are highly interspersed. In order to elucidate the organization of the V _H locus, we set out to construct its physical map by isolation of YAC and P1 clones. Physical mapping and sequencing analysis allowed us to conclude the following :
1. We analyzed the entire human V_H locus by isolation of YAC and P1 clones. Altogether 81 V_H segments belonging to 7 different families were identified within the 1.0-Mb region. The total number of the V_H segments is calculated to be 81, with additional 7, or more, polymorphic V_H segments.
2.A phylogenetic tree of 33 potentially functional V_H segments clearly supported the previous classification of human V_H segments into 7 families. Unidirectional transfer of segmental sequences was identified within the V_H-3 and V_H-4 families, providing clear examples of germline gene conversion.
3. Nucleotide sequence analysis of the entire locus is in progress. A Primer walking method was employed to avoid possible confusion in assembly of the sequences due to the repetitive nature of the locus. To date, we have determined the nucleotide sequence of approximately 600-kb DNAs.
4. The translocated V_H region on 16p11 consists of 7 V_H segments. The D_5 locus was mapped to 15q11-12. The putative ancestor of these regions was found within the V_H locus on chromosome 14. Comparison of V_H sequences suggested that the two orphon loci might have been translocated simultaneously about 20 Myr ago.
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