KRT4（角蛋白4）属于角蛋白基因家族，是一种中间纤维蛋白，主要在上皮细胞中表达，特别是在非角化复层鳞状上皮中，如口腔、食道和阴道黏膜。KRT4与其配对蛋白KRT13共同形成异二聚体，构成细胞骨架网络，维持上皮细胞的机械强度和结构完整性。KRT4在细胞分化、组织修复和屏障功能中起关键作用。KRT4突变可能导致细胞骨架不稳定，与多种遗传性皮肤病相关，如白色海绵状痣（White Sponge Nevus），这是一种良性黏膜病变，表现为口腔和生殖器黏膜的白色增厚斑块。KRT4突变通常为错义突变，影响蛋白质的螺旋结构域，破坏其与KRT13的结合能力，导致角蛋白纤维组装异常。KRT4过表达可能干扰正常角蛋白网络的形成，影响上皮细胞的机械性能和分化过程，而降低表达可能导致上皮脆弱，增加组织损伤风险。角蛋白家族（KRT基因家族）包含超过50个成员，分为I型（酸性）和II型（中性-碱性）角蛋白，它们通过异二聚体形式组装成中间纤维，为上皮细胞提供结构支持并参与细胞信号传导。该家族成员具有高度组织特异性表达模式，并在应激响应、伤口愈合和癌症进展中发挥作用。KRT4作为I型角蛋白，其功能异常不仅与遗传性疾病相关，也可能影响上皮屏障功能，增加炎症或癌变风险。

由该基因编码的蛋白质是角蛋白基因家族的一个成员。 II型角蛋白包括被布置成对简单和分层上皮组织分化过程中共同表达异型角蛋白链的碱性或中性的蛋白质。这种II型细胞角蛋白在粘膜和食管黏膜与家庭成员KRT13的差异化层具体表现。在这些基因中的突变已与白色海绵痣，其特征在于通过口服，食管，和肛门粘膜白斑相关联。 II型角蛋白聚集在染色体12q12-Q13的一个区域。 [由RefSeq的，2008年7月提供]

KRT4, a member of the keratin gene family, encodes a type I (acidic) intermediate filament protein that is predominantly expressed in non-keratinized stratified squamous epithelia, including the mucosal linings of the oral cavity, esophagus, and vagina. Within these tissues, KRT4 forms stable heterodimers with its partner, the type II keratin KRT13, to assemble the cytoskeletal network essential for maintaining the mechanical integrity and structural resilience of epithelial cells. This filamentous architecture plays a pivotal role in cell differentiation, tissue repair, and the preservation of epithelial barrier function. Genetic alterations in KRT4, typically missense mutations that disrupt the alpha-helical coiled-coil domains, impair the protein's ability to bind KRT13, leading to defective keratin fiber assembly and cytoskeletal instability. Such defects are clinically manifested in conditions like White Sponge Nevus, a benign hereditary mucosal disorder characterized by white, thickened plaques on the oral and genital mucosa. Beyond its role in genetic disorders, the dysregulation of KRT4 expression can significantly impact tissue homeostasis; overexpression may interfere with normal keratin network formation and epithelial differentiation, while reduced expression compromises epithelial fragility, thereby increasing susceptibility to tissue injury, inflammation, and potentially cancer progression. As part of a broader family of over 50 keratin genes that exhibit high tissue-specificity and participate in stress responses and wound healing, KRT4 is critical not only for structural support but also for modulating cellular signaling pathways that govern epithelial health and disease susceptibility.

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