Table 1. Characteristics of cytokeratin and vimentin intermediate filament types.

Individual types of intermediate filaments are categorized by primary method of assembly, tissue location, isoelectric point (pI), molecular weight, and expressed proteins in a given category.

Category	Primary assembly method	Tissue expression	pI	MW (kDa)	Protein(s)
Type I Cytokeratins	Heteropolymerize with Type II	Epithelial cells	Acidic (4.5 – 6.0)	40 – 56.5	K9, 10, 12–20, 23–28, 31–40
Type II Cytokeratins	Heteropolymerize with Type I	Epithelial cells	Basic (6.5 – 8.5)	50 – 70	K1–8, 71–86
Vimentin	Homopolymerize	Mesenchymal cells	Acidic (5.6)	57	Vimentin