PMID: 4055801

 

    Legend: Gene, Sites

Title : The architecture of complement component C9 and poly( C9 )

Abstract :
  1. The architecture of human complement component C9 and poly( C9 ) was investigated by transmission electron microscopy
  2. Monomeric native C9 (Mr = 66,000) exhibits an ellipsoid appearance (70 X 50 A) with a crevice visible on one face
  3. C9 polymerizes spontaneously to form hollow tubular structures consisting of 12-16 monomeric subunits
  4. Poly(C9 ) is a cylinder (150 A-outer diameters and 90 A-inner diameter) rimmed by a torus (46-A thick) on one end
  5. Electron micrographs of poly( C9 ) indicate that the torus is formed by radial strands of polypeptide
  6. Each subunit of poly( C9 ) is apparently tilted relative to the central axis of the cylindrical structure
  7. C9 can be cleaved by alpha- thrombin into two single-chain polypeptide fragments : C9a (Mr = 28,000) and C9b (Mr = 38,000), which are the amino- and carboxyl-terminal segments of the protein , respectively
  8. The cleaved form of the protein , C9a,b, can be induced to polymerize under suitable conditions to form sodium dodecyl sulfate-resistant poly( C9 ), indicating that the resistance of poly( C9 ) to denaturation is a collective feature of both C9a and C9b
  9. The C9a and C9b polypeptide regions have been mapped on poly( C9 ) by immunoelectron microscopy
  10. Determinants for the C9a region were observed about the torus, base, and on the midsection of the poly( C9 ) cylinder
  11. C9b epitopes are concentrated predominantly about the torus and base, but were rarely observed on the midsection of poly( C9 )
  12. Thus, the C9a and C9b segments of the C9 polypeptide are not clearly segregated in poly( C9 )
  13. The locations of oligosaccharide units on poly( C9 ) were visualized by electron microscopy after labeling of the complex with concanavalin A bound to colloidal gold
  14. The oligosaccharide positions were found on the periphery of the torus and base
  15. In summary, C9 appears to be a single-domain protein
  16. Polymerization involves a major rearrangement
  17. To form a subunit of poly( C9 ) the polypeptide chain must form at least one major fold parallel to the central axis of the tubule
Output (sent_index, trigger, protein, sugar, site):
Output(Part-Of) (sent_index, protein, site):
  • 12. C9, polypeptide
  • 7. polypeptide, fragments
  • 7. protein, fragments
  • 9. C9b, regions
  • 9. polypeptide, regions
*Output_Site_Fusion* (sent_index, protein, sugar, site):

 

 

Protein NCBI ID SENTENCE INDEX
thrombin 2147 7
complement component C9 735 0,1