Intermediate Filament Types

TYPE I & II

The 28 type I and 26 type II intermediate filament proteins are the keratins (sometimes called cytokeratins), and account for most of the intermediate filaments (i.e. 54 genes out of the total of 70 human intermediate filament genes). Keratins only assemble as heteropolymers: a type I and a type II protein forming a heterodimer. Each keratin pair is characteristic of a particular epithelial differentiation programme; some epithelial cells express more than one pair. The coexpressed pairs of type I plus type II keratins can be divided into two or three expression groups: simple keratins of one-layered epithelia (e.g. K8/K18, K20), barrier (keratinocyte) keratins of stratified epithelia (e.g. K5/K14, K1/K10, K3/K12, K4/K13, K6a/K16, K6b/K17, K19) and structural keratins which make up hard appendages like hair, nails, horns and reptilian scales. The new keratin nomenclature is used according to Schweizer et al 2006, J. of Cell Biol., Volume 174, Issue 2, 2006. Pages: 169-174.

TYPE I

K9	K10	K12	K13	K14
K15	K16	K17	K18	K19
K20	K23	K24	K25 (K25irs1)	K26 (K25irs2)
K27 (K25irs3)	K28 (K25irs4)	K31 (Ha1)	K32 (Ha2)	K33a (Ha3-I)
K33b (Ha3-II)	K34 (Ha4)	K35 (Ha5)	K36 (Ha6)	K37 (Ha7)
K38 (Ha8)	K39 (Ka35)	K40 (Ka36)

TYPE II

K1	K2 (K2e)	K3	K4	K5
K6a	K6b	K6c (K6e/h)	K7	K8
K71 (K6irs1)	K72 (K6irs2)	K73 (K6irs3)	K74 (K6irs4)	K75 (K6hf)
K76 (K2p)	K77 (K1b)	K78 (K5b)	K79 (K6l)	K80 (Kb20)
K81 (Hb1)	K82 (Hb2)	K83 (Hb3)	K84 (Hb4)	K85 (Hb5)
K86 (Hb6)

Click here for statistics of type I & II intermediate filament proteins.

Last modified: August 27 2008 16:55:25.