{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMarapsin, a tryptic serine protease encoded by PRSS27, is preferentially expressed in stratified squamous epithelia. In human tissues, it is normally found in nonkeratinizing epithelia such as the esophagus, tonsil, cervix, larynx, and cornea, while its expression in keratinizing epidermis is induced during hyperproliferative conditions like psoriasis and wound healing. Its transient up-regulation parallels the process of re‐epithelialization and terminal keratinocyte differentiation, where cytokines such as IL‐22 may modulate its expression."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nComparative studies in human and mouse models reveal that, although marapsin is evolutionarily conserved as a tryptic peptidase, its molecular form varies: human marapsin lacks the transmembrane anchor present in the mouse enzyme, a result of a nonsense mutation in ancestral apes. Despite its unique substrate selectivity and resistance to classical protease inhibitors, genetic ablation of marapsin in mice does not result in overt epithelial or developmental defects, suggesting functional redundancy in epithelial differentiation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Wei Li, Dimitry M Danilenko, Stuart Bunting, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The serine protease marapsin is expressed in stratified squamous epithelia and is up-regulated in the hyperproliferative epidermis of psoriasis and regenerating wounds."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2009)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M806267200"}], "href": "https://doi.org/10.1074/jbc.M806267200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "18948266"}], "href": "https://pubmed.ncbi.nlm.nih.gov/18948266"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Kavita Raman, Neil N Trivedi, Wilfred W Raymond, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Mutational tail loss is an evolutionary mechanism for liberating marapsins and other type I serine proteases from transmembrane anchors."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M112.449033"}], "href": "https://doi.org/10.1074/jbc.M112.449033"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23447538"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23447538"}]}]}]}