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Complementary DNA cloning of complement C8 beta and its sequence homology to C9
J A Haefliger1, J Tschopp, D Nardelli
1Institut de Biochimie, Université de Lausanne, Epalinges, Switzerland.
Biochemistry
|June 16, 1987
Summary
Researchers determined the amino acid sequence of C8 beta from human liver cDNA. This protein shows homology to C9, particularly in key functional regions, suggesting a role in membrane attack complex formation.
Area of Science:
- Molecular Biology
- Immunology
- Proteomics
Background:
- The complement system is crucial for innate and adaptive immunity.
- The Membrane Attack Complex (MAC) is a key effector of complement-mediated cell lysis.
- Understanding the structure and function of MAC components like C8 beta is vital.
Purpose of the Study:
- To elucidate the complete amino acid sequence of mature C8 beta.
- To compare the sequence of C8 beta with C9 to identify conserved regions.
- To explore the implications of these findings for MAC formation mechanisms.
Main Methods:
- cDNA library screening using expression analysis.
- DNA sequencing to derive amino acid sequences.
- Bioinformatic comparison of protein sequences.
Main Results:
- The complete amino acid sequence of mature C8 beta was determined from a human liver cDNA clone.
- C8 beta exhibits significant overall homology to C9, with minor sequence variations.
- Crucial domains, including cysteine-rich and membrane-inserting regions, are well-conserved between C8 beta and C9.
Conclusions:
- The sequence homology supports a conserved structural and functional role for C8 beta and C9 in the MAC.
- Conserved regions likely play critical roles in the assembly and membrane insertion of the MAC.
- These findings provide insights into the molecular mechanisms underlying MAC formation and pore formation in target membranes.