Type I keratin involved in the formation and maintenance of various skin appendages, specifically in determining shape and orientation of hair (PubMed:14714564, PubMed:16702408). Required for the correct growth of hair follicles, in particular for the persistence of the anagen (growth) state (PubMed:16702408). Modulates the function of TNF-alpha in the specific context of hair cycling. Regulates protein synthesis and epithelial cell growth through binding to the adapter protein SFN and by stimulating Akt/mTOR pathway (PubMed:16710422). Involved in tissue repair. May be a marker of basal cell differentiation in complex epithelia and therefore indicative of a certain type of epithelial 'stem cells'. Acts as a promoter of epithelial proliferation by acting a regulator of immune response in skin: promotes Th1/Th17-dominated immune environment contributing to the development of basaloid skin tumors (PubMed:20871598). May act as an autoantigen in the immunopathogenesis of psoriasis, with certain peptide regions being a major target for autoreactive T-cells and hence causing their proliferation. Heterodimer of a type I and a type II keratin. KRT17 associates with KRT6 isomers (KRT6A or KRT6B) (By similarity). Interacts with TRADD and SFN. Expressed strongly in outer root sheath and medulla region of hair follicle and in the early differentiating epithelial cells (trichocytes) within the hair bulb region. Weak expression in the matrix cells of hair bulb. Also present in the sweat gland within the skin, vibrissae follicle, salivary gland, tooth and thymus. Expression first occurs in a subset of epithelial cells within the single-layered, undifferentiated ectoderm of embryonic day 10.5 mouse fetuses (PubMed:9786956). In the ensuing 48 hours, K17-expressing cells give rise to placodes, the precursors of ectoderm-derived appendages (hair, glands, and tooth), and to periderm (PubMed:9786956). Expressed in hair follicles and in the basal and suprabasal layers of the interfollicular epidermis at birth (PubMed:11408584). Induced in damaged or stressed epidermis and by interferon-gamma. Up-regulated by LEF1. Phosphorylation at Ser-44 occurs in a growth- and stress-dependent fashion in skin keratinocytes, it has no effect on filament organization. Severe alopecia during the first week postbirth, correlating with hair fragility, alterations in follicular histology, and apoptosis in matrix cells. There are two types of cytoskeletal and microfibrillar keratin: I (acidic; 40-55 kDa) and II (neutral to basic; 56-70 kDa). Belongs to the intermediate filament family.