Primary structure of human pepsinogen gene

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Pepsinogen is a precursor to pepsin, a key digestive enzyme.
• Understanding pepsinogen gene structure is crucial for insights into digestive enzyme evolution and function.

Purpose of the Study:

• To isolate and characterize the human pepsinogen gene.
• To analyze the structure and evolutionary origins of the human pepsinogen gene.

Main Methods:

• Screening a human genomic DNA library using a swine pepsinogen cDNA probe.
• DNA sequence analysis of the isolated recombinant clone.

Main Results:

• Isolation of a recombinant clone containing the complete human pepsinogen gene (approx. 9.4 kb).
• The gene comprises nine exons separated by eight introns.
• Predicted human pepsinogen sequence (373 residues) shows 82% homology to swine pepsinogen.
• Identified a 15-amino acid N-terminal signal sequence, indicating synthesis as prepepsinogen.

Conclusions:

• The human pepsinogen gene structure supports the hypothesis of evolution via duplication of an ancestral gene.
• The presence of homologous sequences for active site residues in different exons suggests a duplication event.