Cell Biology

A Good Amyloid

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Science  09 Dec 2005:
Vol. 310, Issue 5754, pp. 1587
DOI: 10.1126/science.310.5754.1587c

Amyloids are an insoluble fibrous form of protein aggregates and are generally associated with a variety of neurodegenerative disease states. Fowler et al. find that in melanocytes, intracellular amyloid is not a pathological aberration but instead plays a productive role in melanin formation. Melanin is a tyrosine-based polymer that protects organisms from some toxins and ultraviolet radiation. In mammalian melanocytes, melanin is produced within membrane-bound organelles known as melanosomes, with the aid of the protein Pmel17. During this process, it appears that Pmel17 adopts an amyloid-like structure that provides a template for the assembly of melanin precursors, and recombinant Pmel17 amyloid was observed to accelerate melanin production in vitro. Within the cell, the Pmel17-containing amyloid could also serve to sequester highly reactive intermediates in melanin biosynthesis. — SMH

PLoS Biol. 4, e6 (2006).

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