International Journal of Molecular Sciences Review Seeing Keratinocyte Proteins through the Looking Glass of Intrinsic Disorder Rambon Shamilov 1 , Victoria L. Robinson 2 and Brian J. Aneskievich 3,* 1 Graduate Program in Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Connecticut, 69 North Eagleville Road, Storrs, CT 06269, USA;
[email protected] 2 Department of Molecular and Cellular Biology, College of Liberal Arts & Sciences, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269, USA;
[email protected] 3 Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA * Correspondence:
[email protected]; Tel.: +1-860-486-3053 Abstract: Epidermal keratinocyte proteins include many with an eccentric amino acid content (com- positional bias), atypical ultrastructural fate (built-in protease sensitivity), or assembly visible at the light microscope level (cytoplasmic granules). However, when considered through the looking glass of intrinsic disorder (ID), these apparent oddities seem quite expected. Keratinocyte proteins with highly repetitive motifs are of low complexity but high adaptation, providing polymers (e.g., profi- laggrin) for proteolysis into bioactive derivatives, or monomers (e.g., loricrin) repeatedly cross-linked to self and other proteins to shield underlying tissue. Keratohyalin granules developing from liquid– liquid phase separation (LLPS) show that unique biomolecular condensates (BMC) and proteinaceous membraneless organelles (PMLO) occur in these highly customized cells. We conducted bioinfor- matic and in silico assessments of representative keratinocyte differentiation-dependent proteins. This was conducted in the context of them having demonstrated potential ID with the prospect of Citation: Shamilov, R.; Robinson, that characteristic driving formation of distinctive keratinocyte structures.