Table 1. X-ray crystal structures determined of human keratin complexes.

PDB ID & Reference	Resolution	Keratin Complex	Mutation	Domain (Residues)	Physiologic Assembly State	Key Structural Findings
6EC0 [19]	2.98 Å	K1-K10	None	1B (226-331 / 195-296)	A11 heterotetramer	Symmetric knob-pocket interactions in 1B domain are important for proper tetramer and mature IF assembly
6E2J [19]	2.39 Å	K1-K10	K1-S233L	1B (226-331 / 195-296)	A11 heterotetramer	Pathologic K1 mutation S233L creates aberrant hydrophobic interactions leading to keratin aggregation
4ZRY [14]	3.30 Å	K1-K10	None	2B (386-489 / 347-456)	Heterodimer (dimer was disulfide-linked into X-shaped tetramers)	Transdimer homotypic disulfide bond linkage at K10 position C401; a few residue differences significantly alter shape and chemistry of keratin molecular surface because unique residues often align along outer helical ridges of coiled-coil
6UUI This report	2.07 Å	K1-K10	K10-C401A	2B (383-489 / 349-456)	Heterodimer	Highest resolution keratin structure to date; an acidic 2B C-terminus drives an octameric complex of half-staggered anti-parallel 2B heterodimers and a splayed C-terminal tetrameric interface
3TNU [23]	3.01 Å	K5-K14	None	2B (382-476 / 332-421)	Heterodimer (dimer was disulfide-linked into X-shaped tetramers)	Transdimer homotypic disulfide bond linkage at K14 position C367; inter-IF disulfide linkages enable filament cage around nucleus to regulate nuclear shape
6JFV [36]	2.60 Å	K5-K14	K14-C367A	2B (379-476 / 327-421)	Heterodimer	Crystal lattice contacts reflect helix 2B-2B interactions important to proper IF assembly, possibly at the octamer stag