STRUCTURE OF GLOBIN GENE AND ITS MOLECULAR MECHANISM OF SPLICING

The globin gene family encodes the protein subunits of hemoglobin, a crucial component of red blood cells responsible for oxygen transport in the body. The structure of the globin gene is highly conserved across species and consists of several exons and introns. In humans, the globin gene cluster is located on chromosome 11 and chromosome 16, with the major adult hemoglobin genes being HBA1, HBA2, HBB, and HBD.

The globin gene structure typically includes three exons and two introns. Exons are the coding regions of the gene that are transcribed into mRNA and eventually translated into protein. Introns are non-coding regions that are removed during the process of RNA splicing. The presence of introns allows for alternative splicing, leading to the generation of multiple protein isoforms from a single gene.

Molecular Mechanism of Splicing

The process of splicing is essential for generating mature mRNA from pre-mRNA by removing introns and joining exons. It is carried out by a large molecular complex called the spliceosome, which consists of small nuclear ribonucleoproteins (snRNPs) and other associated proteins.

The splicing process involves two sequential transesterification reactions: the first reaction results in the cleavage of the 5’ splice site and formation of a lariat intermediate, while the second reaction leads to the joining of the exons and release of the intron lariat. Splicing is guided by specific sequence elements within the pre-mRNA, including the 5’ splice site, branch point sequence, polypyrimidine tract, and 3’ splice site.

Alternative splicing allows for the production of multiple mRNA transcripts from a single gene, leading to diversity in protein isoforms. This process plays a critical role in regulating gene expression and generating protein diversity in eukaryotic organisms.

In summary, the structure of the globin gene includes exons and introns, with splicing being a crucial molecular mechanism for removing introns and joining exons to generate mature mRNA transcripts.