Factor H

Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large (155 kilodaltons), soluble glycoprotein that circulates in human plasma (at typical concentrations of 200–300 micrograms per milliliter). Its principal function is to regulate the Alternative Pathway of the complement system, ensuring that the complement system is directed towards pathogens or other dangerous material and does not damage host tissue. Factor H regulates complement activation on self cells and surfaces by possessing both cofactor activity for the Factor I mediated C3b cleavage, and decay accelerating activity against the alternative pathway C3-convertase, C3bBb. Factor H exerts its protective action on self cells and self surfaces but not on the surfaces of bacteria or viruses, because it binds to glycosaminoglycans (GAGs) that are generally present on host cells but not, normally, on pathogen surfaces.

Structure and function

FHL1

Four and a half LIM domains protein 1 is a protein that in humans is encoded by the FHL1 gene.

Structure

LIM proteins, named for 'LIN11, ISL1, and MEC3,' are defined by the possession of a highly conserved double zinc finger motif called the LIM domain.

Role in muscle disorders

FHL1 has been shown to be heavily expressed in skeletal and cardiac muscles. In 2008 this was borne out by the discovery that defects in the FHL1 gene are responsible for a number of Muscular dystrophy-like muscle disorders, ranging from severe, childhood onset diseases through to adult-onset disorders similar to Limb girdle muscular dystrophy. At present different research groups are using different terminology for these disorders, which include:

References

Further reading

External links

This article incorporates text from the United States National Library of Medicine, which is in the public domain.