developmental stage:First detected at embryonic week 8 in individual 'converted' simple epithelial cells of the developing intestinal mucosa. In later fetal stages, synthesis extends over most goblet cells and a variable number of villus enterocytes. In the developing gastric and intestinal mucosa, expressed in all enterocytes and goblet cells as well as certain 'low-differentiated' columnar cells, whereas the neuroendocrine and Paneth cells are negative.,function:Plays a significant role in maintaining keratin filament organization in intestinal epithelia. When phosphorylated, plays a role in the secretion of mucin in the small intestine.,miscellaneous:There are two types of cytoskeletal and microfibrillar keratin: I (acidic; 40-55 kDa) and II (neutral to basic; 56-70 kDa).,PTM:Hyperphosphorylation at Ser-13 occurs during the early stages of apoptosis but becomes less prominent during the later stages. Phosphorylation at Ser-13 also increases in response to stress brought on by cell injury.,PTM:Proteolytically cleaved by caspases during apoptosis. Cleavage occurs at Asp-228.,similarity:Belongs to the intermediate filament family.,subunit:Heterotetramer of two type I and two type II keratins. Associates with KRT8.,tissue specificity:Expressed predominantly in the intestinal epithelium. Expressed in luminal cells of colonic mucosa. Also expressed in the Merkel cells of keratinized oral mucosa; specifically at the tips of some rete ridges of the gingival mucosa, in the basal layer of the palatal mucosa and in the taste buds of lingual mucosa.,
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Function:
apoptosis, cytoskeleton organization, cell death, programmed cell death, death, regulation of protein localization,cellular response to stress, intermediate filament-based process, intermediate filament cytoskeleton organization,intermediate filament organization, regulation of protein secretion, regulation of secretion, regulation of protein transport, regulation of cellular localization, regulation of establishment of protein localization,
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Cellular Localization:
Cytoplasm .
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Tissue Expression:
Expressed predominantly in the intestinal epithelium. Expressed in luminal cells of colonic mucosa. Also expressed in the Merkel cells of keratinized oral mucosa; specifically at the tips of some rete ridges of the gingival mucosa, in the basal layer of the palatal mucosa and in the taste buds of lingual mucosa.