Milk fat globule-EGF factor 8 protein (Mfge8), also known as lactadherin, is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''MFGE8''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Species distribution
Mfge8 is a secreted protein found in vertebrates, including mammals as well as birds.
Function
MFGE8 may function as a cell adhesion protein to connect smooth muscle to elastic fibers in arteries.
An
amyloid fragment of MFGE8 known as medin accumulates in the aorta with
aging
Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
.
MFGE8 in the vasculature of adults can induce recovery from
ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
by facilitating
angiogenesis
Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...
.
It has been suggested that antagonizing MFGE8-induced angiogenesis could be a way of fighting cancer.
MFGE8 contains a
phosphatidylserine (PS) binding domain, as well as an
Arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the am ...
-
Glycine-
Aspartic acid
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
motif, which enables the binding to
integrins. MFGE8 binds PS, which is exposed on the surface of
apoptotic cells.
Opsonization
Opsonins are extracellular proteins that, when bound to substances or cells, induce phagocytes to phagocytose the substances or cells with the opsonins bound. Thus, opsonins act as tags to label things in the body that should be phagocytosed (i.e. ...
of the apoptotic cells and binding to integrins on the surface of
phagocytic cells, mediates the engulfment of the dead cell.
References
Further reading
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