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Molecular cloning and characterization of the gene coding for human complement protein factor B
Summary
Researchers isolated human factor B gene cosmid clones and sequenced the serine proteinase domain of the Bb portion. Key active site residues are located on separate exons, indicating complex gene structure.
Area of Science:
- Genomics
- Molecular Biology
- Biochemistry
Background:
- Factor B is a crucial component of the complement system.
- Understanding the genetic structure of complement proteins is vital for immunology.
Purpose of the Study:
- To isolate and characterize human factor B gene cosmid clones.
- To determine the DNA sequence and structural organization of the Bb portion, including the serine proteinase domain.
Main Methods:
- Isolation of cosmid clones from a human genomic DNA library.
- Hybridization using a cDNA probe for clone identification.
- Restriction endonuclease digestion and Southern blotting for characterization.
- DNA sequencing of the 3' end of the factor B gene.
Main Results:
- Four cosmid clones containing the human factor B gene were isolated.
- A partial restriction map was constructed.
- 3.3 kb of sequence at the 3' end of the Bb portion was determined, encompassing the serine proteinase domain.
- Active site residues (His, Asp, Ser) were found to be on separate exons.
Conclusions:
- The serine proteinase domain of human factor B is encoded by multiple exons.
- Exon-intron structure within this domain suggests complex evolutionary or regulatory mechanisms.