Isolation and analysis of a cDNA coding for human C1 inhibitor

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• C1 inhibitor (C1-INH) is a crucial component of the innate immune system.
• It regulates complement activation and the contact system.
• Understanding C1-INH structure is vital for its function.

Purpose of the Study:

• To isolate and characterize the cDNA coding for human C1 inhibitor.
• To determine the amino acid sequence of a partial C1-INH clone.
• To analyze the reactive site and its homology to other protease inhibitors.

Main Methods:

• cDNA library screening using lambda gt11 expression system.
• DNA sequencing via the dideoxy method.
• Bioinformatic analysis of deduced amino acid sequence.

Main Results:

• A partial cDNA clone coding for 310 amino acids of human C1 inhibitor was successfully isolated.
• The deduced amino acid sequence included the reactive site, confirming its identity.
• The sequence exhibited homology to the superfamily of plasma serine protease inhibitors.
• The cDNA contained a stop codon, a 3' noncoding region, and a polyadenylation signal.

Conclusions:

• The isolated cDNA provides valuable information about the structure of human C1 inhibitor.
• The findings confirm the location of the reactive site and its similarity to other protease inhibitors.
• This research contributes to the understanding of C1-INH's role in biological pathways.