Expression of human T cell receptor-gamma delta structural forms.

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• The human T-cell receptor gamma delta (TCR-gamma delta) exists in three biochemically distinct forms: 1, 2bc, and 2abc.
• These forms differ in the association of TCR gamma-chains and TCR delta-chains, with variations in disulfide linkage and polypeptide size.
• Sequence analysis reveals distinct gene segment usage (C gamma 1 vs. C gamma 2) and exon compositions (CII exon) among the different TCR-gamma delta forms.

Purpose of the Study:

• To investigate the molecular basis for the distinct biochemical forms of human TCR-gamma delta.
• To determine the role of the TCR gamma-chain in controlling disulfide linkage with the TCR delta-chain.
• To elucidate how structural differences, particularly the CII exon, influence glycosylation of TCR gamma-chains.

Main Methods:

• Transfection of TCR-gamma cDNA encoding form 1 or 2abc into the MOLT-13 cell line (expressing form 2bc).
• Analysis of TCR-gamma delta heterodimer formation and CD3 association in transfected cells.
• Comparison of structural and glycosylation patterns between different TCR-gamma delta forms.

Main Results:

• Transfected TCR gamma-chains associated with resident TCR delta-chains to form CD3-associated heterodimers identical to donor cell lines.
• Disulfide linkage between TCR gamma- and TCR delta-chains is controlled by the TCR gamma-chain when TCR delta is available.
• The presence of the CII exon 'a' copy influences N-linked glycosylation of TCR gamma-chains by altering protein structure.

Conclusions:

• TCR gamma-chain structure dictates disulfide linkage with TCR delta-chain.
• Structural variations in TCR gamma-chains, influenced by CII exon composition, affect glycosylation.
• Significant structural differences and unequal representation of TCR-gamma delta forms in peripheral blood suggest potential functional or selection-based disparities.