Diverse organization of immunoglobulin VH gene loci in a primitive vertebrate.

F. Kokubu, R. Litman, M. J. Shamblott, K. Hinds, G. W. Litman

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Abstract

The immunoglobulin (Ig) heavy chain variable (VH) gene family of Heterodontus francisci (horned shark), a phylogenetically distant vertebrate, is unique in that VH, diversity (DH), joining (JH) and constant region (CH) gene segments are linked closely, in multiple individual clusters. The V regions of 12 genomic (liver and gonad) DNA clones have been sequenced completely and three organization patterns are evident: (i) VH-D1-D2-JH-CH with unique 12/22 and 12/12 spacers in the respective D recombination signal sequences (RSSs); VH and JH segments have 23 nucleotide (nt) spacers, (ii) VHDH-JH-CH, an unusual germline configuration with joined VH and DH segments and (iii) VHDHJH-CH, with all segmental elements being joined. The latter two configurations do not appear to be pseudogenes. Another VH-D1-D2-JH-CH gene possesses a D1 segment that is flanked by RSSs with 12 nt spacers and a D2 segment with 22/12 spacers. Based on the comparison of spleen, VH+ cDNA sequences to a germline consensus, it is evident that both DH segments as well as junctional and N-type diversity account for Ig variability. In this early vertebrate, the Ig genes share unique properties with higher vertebrate T-cell receptor as well as with Ig and may reflect the structure of a common ancestral antigen binding receptor gene.

Original languageEnglish (US)
Pages (from-to)3413-3422
Number of pages10
JournalEMBO Journal
Volume7
Issue number11
StatePublished - Nov 1 1988

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ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

Cite this

Kokubu, F., Litman, R., Shamblott, M. J., Hinds, K., & Litman, G. W. (1988). Diverse organization of immunoglobulin VH gene loci in a primitive vertebrate. EMBO Journal, 7(11), 3413-3422.