Peripherin-2 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 ''PRPH2''
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 ...
.
Peripherin-2 is found in the rod and cone cells of the
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
of the
eye
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
. Defects in this protein result in one form of
retinitis pigmentosa
Retinitis pigmentosa (RP) is a genetic disorder of the eyes that causes loss of vision. Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). As peripheral vision worsens, people may ...
, an incurable blindness.
Mutations in the PRPH2 gene are associated with
Vitelliform macular dystrophy
Vitelliform macular dystrophy is an irregular autosomal dominant eye disorder which can cause progressive vision loss. This disorder affects the retina, specifically cells in a small area near the center of the retina called the macula. The macu ...
.
Function
The protein encoded by this gene is a member of the transmembrane 4 superfamily, also known as the
tetraspanin
Tetraspanins are a family of membrane proteins found in all multicellular eukaryotes.
Tetraspanins, also referred to as the transmembrane 4 superfamily (TM4SF) proteins, have four transmembrane alpha-helices and two extracellular domains, one s ...
family. Most of these members are cell-surface proteins that are characterized by the presence of four transmembrane helices. Tetraspanins mediate signal transduction events that play a role in the regulation of cell development, activation, growth and motility.
Peripherin 2 (sometimes referred to as peripherin/RDS or simply RDS) is a cell surface
glycoprotein
Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...
found in the outer segment of both rod and cone photoreceptor cells. It is located in the rim regions of the flattened disks that contain
rhodopsin
Rhodopsin, also known as visual purple, is a protein encoded by the RHO gene and a G-protein-coupled receptor (GPCR). It is the opsin of the rod cells in the retina and a light-sensitive receptor protein that triggers visual phototransduction ...
, which is the protein that is responsible for initiation of visual phototransduction upon reception of light. Peripherin 2 may function as an
adhesion molecule
Cell adhesion molecules (CAMs) are a subset of cell surface proteins that are involved in the binding of cells with other cells or with the extracellular matrix (ECM), in a process called cell adhesion. In essence, CAMs help cells stick to each ...
involved in stabilization and compaction of
outer segment disks or in the maintenance of the curvature of the rim. This protein is essential for disk
morphogenesis
Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of devel ...
.
Clinical significance
Defects in this gene are associated with both central and peripheral retinal degenerations. Some of the various phenotypically different disorders are autosomal dominant
retinitis pigmentosa
Retinitis pigmentosa (RP) is a genetic disorder of the eyes that causes loss of vision. Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). As peripheral vision worsens, people may ...
, progressive
macular degeneration
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, som ...
,
macular dystrophy and retinitis pigmentosa digenic.
References
External links
GeneReviews/NIH/NCBI/UW entry on Retinitis Pigmentosa Overview
Further reading
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