Structure and polymorphism of the HLA class II SB light chain genes

Area of Science:

• Immunogenetics
• Molecular Biology
• Human Leukocyte Antigen (HLA) system

Background:

• The Human Leukocyte Antigen (HLA) Class II region, comprising DR, DC, and SB loci, is vital for immune response.
• HLA Class II antigens are heterodimers of alpha and beta chains, with limited N-terminal protein sequence data available for SB beta chains.

Purpose of the Study:

• To report the sequence of a complete Class II beta cDNA clone for the SB beta chain.
• To elucidate the structure and coding sequence of genomic SB beta clones from two different SB haplotypes.
• To investigate alternative splicing and identify polymorphic regions within the SB beta gene.

Main Methods:

• Sequencing of a complete Class II beta cDNA clone.
• Sequencing of genomic SB beta clones from two distinct SB haplotypes.
• Partial sequencing of a second non-allelic SB beta-like gene (SX beta).

Main Results:

• The cDNA sequence closely matches available N-terminal protein sequence data for the SB beta chain.
• Genomic SB beta clones reveal gene structure, coding sequences, and polymorphic regions.
• Evidence of alternative splicing at the 3' end of the SB beta gene, leading to two distinct intracytoplasmic regions.
• The SX beta gene is identified as a pseudogene.

Conclusions:

• The study provides a comprehensive sequence and structural analysis of the SB beta gene.
• Alternative splicing of the SB beta gene contributes to functional diversity.
• The identification of SX beta as a pseudogene clarifies the genetic landscape of this HLA region.