Question

The major histocompatibility complex (MHC) is located on chromosome 6 in humans and contains more than 200 genes with thousands of correspondent proteins. The expression MHC class I molecules on the cell surface is critical for recognition by cytotoxic T lymphocytes (CTL). This recognition event is an immune response that leads to the destruction of cells displaying MHC class I-viral peptide complexes or cells displaying MHC class I-mutant peptide complexes.

Briefly describe the components of a characteristic transcriptional unit of an MHC gene.

Answer 1

The HLA genes are present on the short arm of chromosome 6.

The gene system here i, the largest cluster in the human genome as it is divided into 3 portions : the genes of class I, class II, and class III,involved in immune system response.

The class 1 codes the alpha polypeptide, where they are coded by different exons present.

Class 2 codes for alpha - beta heterodimers. With similar arrangement of exons , and different domains of polypeptide formed by different exons.

Class 3 region is also Polygenic having many genes coding for C3 , C4 , c5 complements, heat shock proteins etc.