World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0004294367
Reproduction Date:

Title: Properdin  
Author: World Heritage Encyclopedia
Language: English
Subject: Complement system, C5-convertase, Acute hemolytic transfusion reaction, Integrin alphaXbeta2, C3b
Publisher: World Heritage Encyclopedia


complement factor properdin
Symbol CFP
Alt. symbols PFC
Entrez 5199
HUGO 8864
OMIM 300383
RefSeq NM_002621
UniProt P27918
Other data
Locus Chr. X p11.4

Properdin or Factor P is the only known positive regulator of complement activation that stabilizes the alternative pathway convertases. It is found in the blood serum of more complex animals.


  • Structure 1
  • Function 2
  • History 3
  • Deficiency 4
  • External links 5


Properdin is a gamma globulin protein composed of multiple identical protein subunits with a separate ligand-binding site. Native properdin occurs in head-to-tail dimers, trimers and tetramers in the fixed ratio 22:52:28.[1]


It is known that it participates in some specific immune responses. It plays a part in tissue inflammation as well as the engulfing of pathogens by phagocytes. In addition it is known to help to neutralize some viruses.

The properdin promotes the association of C3b with Factor B and provides a focal point for the assembly of C3bBb on a surface. It binds to preformed alternative pathway C3-convertases.[2] Properdin also inhibits the Factor H – mediated cleavage of C3b by Factor I.

Alternative pathway. Properdin is the "P" in the blue circles. (Some labels are in Polish.)

The alternative pathway is not dependent on antibodies. This branch of the complement system is activated by IgA immune complexes and bacterial endotoxins, polysaccharides, and cell walls, and results in producing anaphylatoxins, opsonins, chemotactic factors, and the membrane attack complex, all of which help fight pathogens.


Properdin was discovered in 1954 by Dr. Louis Pillemer of the Institute of Pathology (now the Department of Pathology at Case Western Reserve University).


Properdin deficiency is a rare X-linked disease in which properdin is deficient. Affected individuals are susceptible to fulminant meningococcal disease.[3]

External links

  1. ^ Smith C, Pangburn M, Vogel C-W, and Müller-Eberhard H (1984). "Molecular Architecture of Human Properdin, a Positive Regulator of the Alternative Pathway of Complement". J of Biol Chem 259: R4582–4588. 
  2. ^ Hourcade D (2006). "The Role of Properdin in the Assembly of the Alternative Pathway C3 Convertases of Complement". J of Biol Chem 281: R2128–2132.  
  3. ^ September 01 2005ProperdinDr. Lars Otto Uttenthal
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.