The complete nucleotide sequence of the I-E alpha d immune response gene

Area of Science:

• Immunogenetics
• Molecular Biology
• Genomics

Background:

• The I-E antigen is a critical component of the murine immune response.
• The H-2db haplotype in mice is characterized by the absence of I-E antigen.
• Understanding the genetic basis of I-E antigen absence is crucial for immunogenetic research.

Purpose of the Study:

• To isolate and sequence the complete murine I-E alpha immune response gene of the H-2db haplotype.
• To elucidate the molecular mechanism underlying the lack of I-E antigen synthesis in H-2 mice.
• To compare the murine I-E alpha gene with its human counterpart.

Main Methods:

• Gene isolation and sequencing of the murine I-E alpha gene.
• Analysis of gene organization, including exons and basepair composition.
• Amino acid sequence homology comparison with human HLA-DR alpha chain.
• Investigation of the 5' end of the I-E alpha b gene for defects.

Main Results:

• The complete murine I-E alpha immune response gene (H-2db haplotype) was isolated and sequenced.
• The gene spans 5300 basepairs and is organized into five or six exons.
• The deduced amino acid sequence shows 75% homology to the human HLA-DR alpha chain.
• A deletion in the 5' end of the I-E alpha b gene was identified as the cause for the absence of E alpha chain synthesis.

Conclusions:

• The absence of I-E antigen in H-2 mice is directly linked to a defect in I-E alpha chain synthesis.
• A specific deletion in the 5' region of the I-E alpha b gene causes this synthesis defect.
• This study provides a molecular explanation for a key difference in immune response genes between mouse haplotypes.