Characterization of the human properdin gene

Area of Science:

• Genomics
• Molecular Biology
• Immunology

Background:

• Properdin is a modular protein crucial for the complement system.
• Its structure is characterized by six tandem repeats of a thrombospondin-related sequence (TSR).
• Previous studies described properdin's modular nature based on cDNA sequences.

Purpose of the Study:

• To characterize the genomic structure of the human properdin gene.
• To resolve discrepancies in the published properdin cDNA sequence.
• To investigate the evolutionary origins of modular proteins through gene organization.

Main Methods:

• Cosmid cloning and sequencing of the human properdin gene.
• Analysis of genomic DNA sequence data.
• Alignment analysis of genomic and protein sequences.

Main Results:

• The human properdin gene spans approximately 6 kb and is organized into ten exons.
• Exon-intron boundaries for TSRs 2-5 support the exon shuffling hypothesis for modular protein evolution.
• The sixth TSR is split across two exons, a feature reflected in the protein structure.

Conclusions:

• The genomic organization of the human properdin gene provides insights into the evolution of modular proteins.
• Exon shuffling is supported as a mechanism for generating protein diversity.
• Resolved discrepancies in the properdin sequence enhance understanding of its genetic basis.