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. 1976 Oct 1;144(4):1076–1093. doi: 10.1084/jem.144.4.1076

Alternative pathway of complement: recruitment of precursor properdin by the labile C3/C5 convertase and the potentiation of the pathway

PMCID: PMC2190426  PMID: 978134

Abstract

In this study the physiological role of properdin and the differential subunit composition of the solid phase enzymes of the pathway have been explored. Cell-bound C3 and C5 convertase differ in their C3b requirement. Apparently one molecule of C3b is sufficient to allow formation of C3 convertase (C3b,B), whereas two or more are required for generation of C5 convertase (C3bn,B). This conclusion was drawn from results indicating the critical role of the spacial distribution of C3b molecules on the cell surface in enzyme formation. While the C3/C5 convertase is fully capable of acting on C5 and thereby initiating the assembly of the cytolytic membrane attack complex, it is exceedingly labile and vulnerable to destruction by the C3b inactivator. It is the apparent role of properdin to confer a degree of stability upon the labile enzyme and to protect its C3 convertase function against enzymatic destruction. To achieve these effects, precursor properdin (pre-P) is recruited in a binding-activation reaction by the labile C3/C5 convertase. Multiple C3b molecules appear to be needed for the formation of properdin-activating principle. Three modes of regulation have been described, which involve spontaneous dissociation enzymatic degradation by C3b inactivator and disassembly by beta1H. The functional differences of pre-P and activated properdin (P) were delineated, pre-P displaying a weak affinity for C3b and P the capacity of strong interaction, P generating a soluble C3 convertase in serum and pre-P being unable to do so. Because of the profound differences between native pre-P and the laboratory product P, the question was raised as to whether soluble P represents an unphysiological form of the protein. On the basis of this and other studies, the conclusion was reached that in vitro properdin recruitment constitutes the terminal event of the properdin pathway, and that properdin augments the function of C3/C5 convertase without changing its substrate specificity.

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Selected References

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  1. Brade V., Lee G. D., Nicholson A., Shin H. S., Mayer M. M. The reaction of zymosan with the properdin system in normal and C4-deficienct guinea pig serum. Demonstration of C3- and C5-cleaving multi-unit enzymes, both containing factor B, and acceleration of their formation by the classical complement pathway. J Immunol. 1973 Nov;111(5):1389–1400. [PubMed] [Google Scholar]
  2. Chapitis J., Lepow I. H. Multiple sedimenting species of properdin in human serum and interaction of purified properdin with the third component of complement. J Exp Med. 1976 Feb 1;143(2):241–257. doi: 10.1084/jem.143.2.241. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cooper N. R., Polley M. J., Müller-Eberhard H. J. The second component of human complement (C2): quantitative molecular analysis of its reactions in immune hemolysis. Immunochemistry. 1970 Apr;7(4):341–356. doi: 10.1016/0019-2791(70)90237-5. [DOI] [PubMed] [Google Scholar]
  4. Fearon D. T., Austen K. F. Inhibition of complement-derived enzymes. Ann N Y Acad Sci. 1975 Jun 13;256:441–450. doi: 10.1111/j.1749-6632.1975.tb36070.x. [DOI] [PubMed] [Google Scholar]
  5. Fearon D. T., Austen K. F. Properdin: binding to C3b and stabilization of the C3b-dependent C3 convertase. J Exp Med. 1975 Oct 1;142(4):856–863. doi: 10.1084/jem.142.4.856. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Fearon D. T., Austen K. F. Properdin: initiation of alternative complement pathway. Proc Natl Acad Sci U S A. 1975 Aug;72(8):3220–3224. doi: 10.1073/pnas.72.8.3220. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Fearon D. T., Austen K. F., Ruddy S. Formation of a hemolytically active cellular intermediate by the interaction between properdin factors B and D and the activated third component of complement. J Exp Med. 1973 Dec 1;138(6):1305–1313. doi: 10.1084/jem.138.6.1305. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Götze O., Müller-Eberhard H. J. The role of properdin in the alternate pathway of complement activation. J Exp Med. 1974 Jan 1;139(1):44–57. doi: 10.1084/jem.139.1.44. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Kolb W. P., Haxby J. A., Arroyave C. M., Müller-Eberhard H. J. Molecular analysis of the membrane attack mechanism of complement. J Exp Med. 1972 Mar 1;135(3):549–566. doi: 10.1084/jem.135.3.549. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. LEPOW I. H., NAFF G. B., TODD E. W., PENSKY J., HINZ C. F. Chromatographic resolution of the first component of human complement into three activities. J Exp Med. 1963 Jun 1;117:983–1008. doi: 10.1084/jem.117.6.983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. McConahey P. J., Dixon F. J. A method of trace iodination of proteins for immunologic studies. Int Arch Allergy Appl Immunol. 1966;29(2):185–189. doi: 10.1159/000229699. [DOI] [PubMed] [Google Scholar]
  12. Minta J. O., Lepow I. H. Studies on the sub-unit structure of human properdin. Immunochemistry. 1974 Jul;11(7):361–368. doi: 10.1016/0019-2791(74)90189-x. [DOI] [PubMed] [Google Scholar]
  13. Muller-Eberhard H. J., Nilsson U. R., Dalmasso A. P., Polley M. J., Calcott M. A. A molecular concept of immune cytolysis. Arch Pathol. 1966 Sep;82(3):205–217. [PubMed] [Google Scholar]
  14. Müller-Eberhard H. J., Götze O. C3 proactivator convertase and its mode of action. J Exp Med. 1972 Apr 1;135(4):1003–1008. doi: 10.1084/jem.135.4.1003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Müller-Eberhard H. J., Polley M. J., Calcott M. A. Formation and functional significance of a molecular complex derived from the second and the fourth component of human complement. J Exp Med. 1967 Feb 1;125(2):359–380. doi: 10.1084/jem.125.2.359. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. NILSSON U. R., MUELLER-EBERHARD H. J. ISOLATION OF BETA IF-GLOBULIN FROM HUMAN SERUM AND ITS CHARACTERIZATION AS THE FIFTH COMPONENT OF COMPLEMENT. J Exp Med. 1965 Aug 1;122:277–298. doi: 10.1084/jem.122.2.277. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Podack E. R., Kolb W. P., Müller-Eberhard H. J. Purification of the sixth and seventh component of human complement without loss of hemolytic activity. J Immunol. 1976 Feb;116(2):263–269. [PubMed] [Google Scholar]
  18. Schreiber R. D., Götze O., Müller-Eberhard H. J. Alternative pathway of complement: demonstration and characterization of initiating factor and its properdin-independent function. J Exp Med. 1976 Oct 1;144(4):1062–1075. doi: 10.1084/jem.144.4.1062. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Schreiber R. D., Medicus R. G., Gïtze O., Müller-Eberhard H. J. Properdin- and nephritic factor-dependent C3 convertases: requirement of native C3 for enzyme formation and the function of bound C3b as properdin receptor. J Exp Med. 1975 Sep 1;142(3):760–772. doi: 10.1084/jem.142.3.760. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Stitzel A. E., Spitzer R. E. The utilization of properdin in the alternate pathway of complement activation: isolation of properdin convertase. J Immunol. 1974 Jan;112(1):56–62. [PubMed] [Google Scholar]
  21. Valet G., Cooper N. R. Isolation and characterization of the proenzyme form of the C1r subunit of the first complement component. J Immunol. 1974 May;112(5):1667–1673. [PubMed] [Google Scholar]
  22. Vallota E. H., Götze O., Spiegelberg H. L., Forristal J., West C. D., Müller-Eberhard H. J. A serum factor in chronic hypocomplementemic hephritis distinct from immunoglobulins and activating the alternate pathway of complement. J Exp Med. 1974 May 1;139(5):1249–1261. doi: 10.1084/jem.139.5.1249. [DOI] [PMC free article] [PubMed] [Google Scholar]

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