Details

Autor(en) / Beteiligte

• McCormack, W T
• Tjoelker, L W
• Stella, G
• Postema, C E
• Thompson, C B

Titel

Chicken T-Cell Receptor β-Chain Diversity: An Evolutionarily Conserved Dβ-Encoded Glycine Turn Within the Hypervariable CDR3 Domain

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1991-09, Vol.88 (17), p.7699-7703

Ort / Verlag

United States: National Academy of Sciences of the United States of America

Erscheinungsjahr

1991

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Unlike mammals, chickens generate an immunoglobulin (Ig) repertoire by a developmentally regulated process of intrachromosomal gene conversion, which results in nucleotide substitutions throughout the variable regions of the Ig heavy- and light-chain genes. In contrast to chicken Ig genes, we show in this report that diversity of the rearranged chicken T-cell receptor (TCR) β-chain gene is generated by junctional heterogeneity, as observed in rearranged mammalian TCR genes. This junctional diversity increases during chicken development as a result of an increasing base-pair addition at the Vβ-Dβand Dβ-Jβjoints (where V, D, and J are the variable, diversity, and joining gene segments). Despite the junctional hypervariability, however, almost all functional Vβ-Dβ-Jβjunctions appear to encode a glycine-containing β-turn. Such a turn may serve to position the amino acid side chains of a hypervariable TCR β-chain loop with respect to the antigen-binding groove of the major histocompatibility complex molecule. Consistent with this hypothesis, the germ-line Dβnucleotide sequences of chickens, mice, rabbits, and humans have been highly conserved and encode a glycine in all three reading frames.