High-molecular-weight precursor of epidermal filaggrin and hypothesis for its tandem repeating structure

作者：John D. Lonsdale‐Eccles, Katheryn A. Resing, Rick L. Meek, Beverly A. Dale · 发表于：Biochemistry · 年份：1984 · DOI：10.1021/bi00301a034 · 被引用次数：65 · 研究领域：Bacterial Genetics and Biotechnology、Toxin Mechanisms and Immunotoxins、Antimicrobial Peptides and Activities

Filaggrin is a histidine-rich protein that is intimately involved in mammalian epidermal keratinization. Using a combination of immunologic and in vivo pulse-chase studies with radiolabeled histidine and phosphate, we show that the phosphorylated precursor of both rat and mouse filaggrin has an apparent molecular weight much higher than previously realized (6 X 10(5) and 3.9 X 10(5), respectively). These high-molecular-weight filaggrin precursors can be rapidly labeled with histidine and extracted from the epidermis under denaturing conditions. More than half of the label incorporated in the precursor at 2 h is found in filaggrin at 24 h after injection, even though filaggrin is less than 10% of the size of the precursor. Limited proteolytic digestion of the precursor in vitro results in the formation of an oligomeric series of peptides based on a phosphorylated fragment slightly larger than filaggrin itself. More extensive digestion of this fragment shows that it is composed of filaggrin with few or no additional unrelated peptides, suggesting that the major part of the high-molecular-weight filaggrin precursor must be composed of repeated domains of filaggrin. Because the primary translation product of filaggrin mRNA is large, we propose that these domains are repeated in tandem. In addition, from molecular weight computations and peptide map analyses, we suggest that the filaggrins are themselves composed of multiple repeating units of an unidentified peptide of approximat...