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Oligosaccharide structure of human C4.
Journal of Immunology (Baltimore, Md. : 1950)
|March 1, 1985
Summary
Human complement C4 (component 4) protein glycosylation was analyzed. The alpha-chain has three complex oligosaccharides, and the beta-chain has one high mannose oligosaccharide, while the gamma-chain is not glycosylated.
Area of Science:
- Biochemistry
- Glycobiology
- Immunology
Background:
- Human complement component 4 (C4) is a key protein in the immune system.
- Understanding C4 glycosylation is crucial for its function and potential therapeutic applications.
Purpose of the Study:
- To elucidate the oligosaccharide structure of human C4.
- To investigate the glycosylation patterns of different C4 chains and their relationship to C4 gene products and processing.
Main Methods:
- Purification of human C4 from plasma and HepG2 cell line.
- Analysis of oligosaccharide structures on C4 alpha-, beta-, and gamma-chains.
- Characterization of incompletely processed C4 molecules.
Main Results:
- The alpha- and beta-chains of human C4 are glycosylated; the gamma-chain is not.
- The alpha-chain contains three complex fucosylated oligosaccharides, and the beta-chain has one high mannose oligosaccharide.
- Differences in C4 gene products (C4A and C4B) are attributed to amino acid variations, not carbohydrate modifications.
Conclusions:
- Intracellular processing to the multi-chain form is not essential for correct oligosaccharide processing in C4.
- The study provides detailed insights into the glycosylation of human C4, contributing to our understanding of complement system biochemistry.