What is Pmel17?

Melanocyte protein PMEL also known as premelanosome protein (PMEL) or silver locus protein homolog (SILV) is a protein that in humans is encoded by the PMEL gene. Its gene product may be referred to as PMEL, silver, ME20, gp100 or Pmel17.

Where are melanosomes found?

skin
Melanosomes are synthesised in the skin in melanocyte cells, as well as the eye in choroidal melanocytes and retinal pigment epithelial (RPE) cells. In lower vertebrates, they are found in melanophores or chromatophores.

How do melanosomes contribute to skin color?

Melanosomes are organelles where melanin pigment is synthesized within skin melanocytes, in retinal pigment epithelium and choroidal melanocytes. In dark skin, melanosomes appear isolated, whereas in white skin they are rather clustered, forming the so-called melanosome complexes or packages (Szabo et al., 1969).

Do melanosomes produce melanin?

Melanosomes are intracellular organelles that are uniquely generated by pigment cells in the skin and eye, where they function to synthesize and store melanin pigments.

Are melanosomes lysosomes?

Melanosomes are lysosome-related organelles within which melanin pigments are synthesized and stored in melanocytes and retinal pigment epithelial cells.

What is the difference between melanocytes and melanosomes?

Melanocytes produce specific organelles, termed melanosomes, in which melanin pigment is synthesized and deposited. In the skin, melanosomes are transferred from melanocytes to neighboring keratinocytes in order to form perinuclear melanin caps (Hearing, 2005).

What mediates melanin release?

Allomelanin and pyomelanin are two types of nitrogen-free melanin. In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Melanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation….

What are the specialized lysosomes?

Lysosomes are specialized organelles that break up macromolecules, allowing the cell to reuse the materials.

Are melanosomes degraded through lysosomal activity?

Melanin appears to be very resistant to lysosomal digestion in vitro. It is assumed, therefore, that in the compound melanosomes, the melanosomes can be degraded by lysosomes at the protein moiety but not at the melanin moiety.

Do keratinocytes have melanosomes?

Melanosomes in lightly pigmented skin–derived keratinocytes are often distributed in membrane-bound clusters of melanosomes, whereas melanosomes in darkly pigmented skin–derived keratinocytes are predominantly individually dispersed (Minwalla et al., 2001; Thong et al., 2003).

Why do melanocytes produce melanin?

Melanocytes produce melanin, a brown pigment that is responsible for skin coloration and protecting against the harmful effects of UV light.

Which vitamin produces melanin?

You get vitamin A from the food you eat, especially vegetables that contain beta carotene, such as carrots, sweet potatoes, spinach, and peas. Since vitamin A also functions as an antioxidant, some researchers believe this vitamin, more than any other, may be the key to melanin production.

What is the function of Pmel17 in melanin?

The PMEL17 (SILV) protein catalyzes the polymerization of 5,6-dihydroxyindole-2-carboxylic acid to melanin. Pmel17 is proteolytically processed in a post-Golgi compartment and is enriched in multivesicular endosomes prior to incorporation in stage II melanosomes.

What kind of protein is encoded in the PMEL gene?

This gene encodes a melanocyte-specific type I transmembrane glycoprotein. The encoded protein is enriched in melanosomes, which are the melanin-producing organelles in melanocytes, and plays an essential role in the structural organization of premelanosomes.

Which is part of the melanosome produces melanin?

The encoded protein is enriched in melanosomes, which are the melanin-producing organelles in melanocytes, and plays an essential role in the structural organization of premelanosomes. This protein is involved in generating internal matrix fibers that define the transition from Stage I to Stage II melanosomes.

How are PMEL mutations related to amyloid fibrils?

PMEL mutations can model the conversion between physiological and pathological amyloid the multistep processing of Pmel17 begins with an early cleavage during secretion that primes the protein for later functional processing. Repeat domains of melanosome matrix protein Pmel17 orthologs form amyloid fibrils at the acidic melanosomal pH.