Type I Keratin

Predicted MW (human): 62 kDa
Observed MW (SDS-PAGE, human): 64 kDa
Isoelectric point (human): 5.4 (R. Moll et al., Cell 1982)

Distribution: K9 is expressed in the post-mitotic, differentiating layers of palmar and plantar epidermis, where its partner is presumably K1. It does not occur in normal interfollicular epidermis of trunk skin.

Gene cloning and nucleotide sequence

Human:     L. Langbein et al., Differentiation 1993 (cDNA)
                 See GenBank Accession Number NM_000226

Mouse sequence is not available

Predicted amino acid sequence

Null mutation phenotype

Unknown.

Involvement in human disease

Inherited mutations in keratin 9 causes epidermolytic palmoplantar
keratinocerma (EPPK), a disorder related to EHK. As suggested by its clinical name, this disease affects palmar and plantar skin, in which the suprabasal differentiating layers rupture in response to mechanical trauma. Patients with EPPK exhibit severe and diffuse thicknening and palmar and plantar skin.