Functional Amyloids As Natural Storage of Peptide Hormones in Pituitary Secretory Granules

TLDR

Amyloid protein aggregation is linked to many diseases, yet functional amyloids such as fungal prions, bacterial curli, silkworm chorion, and mammalian Pmel‑17 exist, suggesting the amyloid fold is an ancient, evolutionarily conserved motif with diverse physiological roles. Maji et al. propose that endocrine hormone peptides and proteins are stored in an amyloid‑like state within secretory granules.

Abstract

Plethora of Secretory Amyloids Protein aggregation and the formation of amyloids are associated with several dozen pathological conditions in humans, including Alzheimer's disease, Parkinson's disease, and type II diabetes. In addition, a few functional amyloid systems are known: the prions of fungi, the bacterial protein curli, the protein of chorion of the eggshell of silkworm, and the amyloid protein Pmel-17 involved in mammalian skin pigmentation. Now Maji et al. (p. 328 , published online 18 June) propose that endocrine hormone peptides and proteins are stored in an amyloid-like state in secretory granules. Thus, the amyloid fold may represent a fundamental, ancient, and evolutionarily conserved protein structural motif that is capable of performing a wide variety of functions contributing to normal cell and tissue physiology.