Related Experiment Videos
Complete amino acid sequences of the three collagen-like regions present in subcomponent C1q of the first component
Insights
The complete amino acid sequences of the collagen-like regions in human subcomponent C1q A-, B-, and C-chains were determined. These sequences reveal interruptions in the typical Gly-X-Y repeating pattern within each chain.
Area of Science:
- Biochemistry
- Molecular Biology
- Immunology
Background:
- Human subcomponent C1q is a key initiator of the classical complement pathway.
- The collagen-like regions of C1q chains are crucial for its function.
- Previous studies have established partial sequences of C1q chains.
Purpose of the Study:
- To determine the complete amino acid sequences of the collagen-like regions of human C1q A-, B-, and C-chains.
- To compare the collagen-like sequences across the different chains of human C1q.
- To identify any deviations from the canonical Gly-X-Y triplet repeat in these regions.
Main Methods:
- Amino acid sequencing of specific residue segments (A-chain: 38-51, C-chain: 42-90).
- Integration of newly determined sequences with previously published data.
- Comparative analysis of complete collagen-like region sequences.
Main Results:
- The complete amino acid sequences for the collagen-like regions of human C1q A-, B-, and C-chains were elucidated.
- Each chain exhibits interruptions in the conserved Gly-X-Y repeating triplet amino acid sequence.
- Specific substitutions were identified: alanine at B-9 and C-36 (where glycine is expected), and threonine at A-39.
Conclusions:
- The collagen-like regions of human C1q chains are not perfectly continuous Gly-X-Y repeats.
- These sequence variations may have functional implications for C1q structure and complement activation.
- Detailed sequence information provides a basis for understanding C1q structure-function relationships.
Abstract:
The sequences of amino acid residues 38--51 of the A-chain, and residues 42--90 of the C-chain, of human subcomponent C1q are given. These results, along with previously published sequence data [Reid (1974) Biochem.J. 141, 189--203; Reid (1977) Biochem.J. 161, 247--251; Reid & Thompson (1978) Biochem.J. 173, 863--868] allow the presentation, and comparison with each other, of the complete amino acid sequences of the collagen-like regions found in the A-, B- and C-chains of human subcomponent C1q. Each chain has the continuity of its collagen-like Gly-X-Y repeating triplet amino acid sequence broken. The B- and C-chains have alanine residues at positions B-9 and C-36 where glycine might be expected. The A-chain has a threonine residue at position A-39, which is located between two Gly-X-Y triplets.