Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large (155 kilodalton), soluble glycoprotein that circulates in human plasma (at a concentration of 500-800 micrograms per mL). Its main job is to regulate the Alternative Pathway of the complement system, ensuring that the complement system is directed towards pathogens and does not damage host tissue. Factor H regulates complement activation on self cells by possessing both cofactor activity for Factor I mediated C3b cleavage, and decay accelerating activity against the alternative pathway C3 convertase, C3bBb. Factor H protects self cells from complement activation but not bacteria/viruses, in that it binds to glycosaminoglycans (GAGs) that are present on host cells but not pathogen cell surfaces. Hugo is a masculine name. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The National Center for Biotechnology Information (NCBI) is part of the US National Library of Medicine (NLM), which is a branch of the US National Institutes of Health. ... Swiss-Prot is a curated biological database of protein sequences created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute. ... The Protein Data Bank (PDB) is a repository for 3-D structural data of proteins and nucleic acids. ... Short and long arms Chromosome. ... Chromosome 1 is, by convention, the designation for the largest human chromosome. ... Look up plasma in Wiktionary, the free dictionary. ... The classical and alternative complement pathways. ... A complement protein attacking an invader. ... A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... Wikipedia does not yet have an article with this exact name. ...

Structure of Factor H

The molecule is made up of 20 Complement Control Protein (CCP) modules (also refered to as Short Consensus Repeats or sushi domains) arranged head to tail. Each of the CCP modules consists of around 60 amino acids with four cysteine residues disulphide bonded in a 1-3 2-4 arrangement, and a hydrophobic core built around an almost invariant tryptophan residue. To date atomic structures have been determined for CCP 5, CCP 7 (both 402H & 402Y), CCP 15, CCP 16, CCPs 15-16, and CCPs 19-20. Although an atomic resolution structure for intact factor H has not yet been determined lower resolutions techniques indicate that it is bent back in solution. Phenylalanine is one of the standard amino acids. ... Cysteine is a naturally occurring amino acid which has a thiol group and is found in most proteins, though only in small quantities. ... A disulfide bond (SS-bond), also called a disulfide bridge, is a strong covalent bond between two sulfhydryl groups. ... Tryptophan is an amino acid and essential in human nutrition. ...

Association with age-related macular degeneration

Recently is was discovered that about 35% of individuals carry at an at-risk single nucleotide polymorphism (SNP) in one or both copies of their factor H gene. Homozygous individuals have an approximately seven-fold increased chance of developing age-related macular degeneration, while heterozygotes have a two-to-three-fold increased likelihood of developing the disease. This SNP is located in CCP module 7, a region of factor H which is known to bind to both C-reactive protein and polyanions including heparin and heparan sulphate. A Single Nucleotide Polymorphism or S.N.P. (pronounced snip) is a DNA sequence variation occurring when a single nucleotide - A, T, C, or G - in the genome (or other shared sequence) differs between members of a species (or between paired chromosomes in an individual). ... Homozygote cells are diploid or polyploid and have the same alleles at a locus (position) on homologous chromosomes. ... This article or section should be merged with macular degeneration Treatment Those with AMD can sometimes benefit from the treatment tested in the Age-Related Eye Disease Study. ... Heterozygote cells are diploid or polyploid and have different alleles at a locus (position) on homologous chromosomes. ... C-reactive protein (CRP) is a plasma protein, an acute phase protein produced by the liver. ... Heparin is a highly sulfated glycosaminoglycan widely used as an injectable anticoagulant. ... Heparan Sulfate (HS) is a linear polysaccharide found in all animal tissues. ...

Sources

• Pangburn, M.K. Host recognition and target differentiation by factor H, a regulator of the alternative pathway of complement. Immunopharmacology 49, 149-57 (2000).
• Kirkitadze, M.D. & Barlow, P.N. Structure and flexibility of the multiple domain proteins that regulate complement activation. Immunol Rev 180, 146-61 (2001).
• Hageman, G.S. et al. A common haplotype in the complement regulatory gene factor H (HF1/CFH) predisposes individuals to age-related macular degeneration. Proc Natl Acad Sci U S A 102, 7227-32. (2005).
• Kardys, I. et al. A common polymorphism in the complement factor h gene is associated with increased risk of myocardial infarction the rotterdam study. J Am Coll Cardiol. 47, 1568-75. (2006).

External links

• MeSH Complement+Factor+H