Melanophilin is a
carrier protein
A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane ...
which in humans is encoded by the ''MLPH''
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 ...
.
Several
alternatively spliced
Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be in ...
transcript variants of this gene have been described, but the full-length nature of some of these variants has not been determined.
Function
This gene encodes a member of the
exophilin subfamily of Rab effector proteins. The protein forms a ternary complex with the small Ras-related GTPase
Rab27A in its GTP-bound form and the motor protein myosin Va.
A similar protein complex in mouse functions to tether pigment-producing organelles called
melanosome
A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotection i ...
s to the
actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over ...
cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compos ...
in melanocytes, and is required for visible pigmentation in the hair and skin.
In melanocytic cells MLPH gene expression may be regulated by
MITF
Microphthalmia-associated transcription factor also known as class E basic helix-loop-helix protein 32 or bHLHe32 is a protein that in humans is encoded by the ''MITF'' gene.
MITF is a basic helix-loop-helix leucine zipper transcription factor ...
.
Clinical significance
A mutation in this gene results in
Griscelli syndrome type 3
Griscelli syndrome type 3 is a disorder of melanosome transport presenting initially with hypopigmentation.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. .
See ...
, which is characterized by a silver-gray hair color and abnormal pigment distribution in the hair shaft.
Mutations in melanophilin cause the "dilute" coat color phenotype in dogs
and cats.
Variation in this gene appears to have been a target for recent
natural selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
in humans, and it has been hypothesized that this is due to a role in human pigmentation.
References
Further reading
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External links
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Human proteins
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