National Eye Institute, National Institutes of Health, Bethesda, Maryland.
National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland.
Pigment Cell Melanoma Res. 2019 Nov;32(6):753-765. doi: 10.1111/pcmr.12791. Epub 2019 Jun 3.
Tyrosinases are melanocyte-specific enzymes involved in melanin biosynthesis. Mutations in their genes cause oculocutaneous albinism associated with reduced or altered pigmentation of skin, hair, and eyes. Here, the recombinant human intra-melanosomal domains of tyrosinase, TYRtr (19-469), and tyrosinase-related protein 1, TYRP1tr (25-472), were studied in vitro to define their functional relationship. Proteins were expressed or coexpressed in whole Trichoplusia ni larvae and purified. Their associations were studied using gel filtration and sedimentation equilibrium methods. Protection of TYRtr was studied by measuring the kinetics of tyrosinase diphenol oxidase activity in the presence (1:1 and 1:20 molar ratios) or the absence of TYRP1tr for 10 hr under conditions mimicking melanosomal and ER pH values. Our data indicate that TYRtr incubation with excess TYRP1tr protects TYR, increasing its stability over time. However, this mechanism does not appear to involve the formation of stable hetero-oligomeric complexes to maintain the protective function.
酪氨酸酶是参与黑色素生物合成的黑素细胞特异性酶。其基因的突变会导致眼皮肤白化病，伴有皮肤、头发和眼睛的色素沉着减少或改变。在这里，研究了重组人黑素体内酪氨酸酶的结构域 TYRtr（19-469）和酪氨酸酶相关蛋白 1，TYRP1tr（25-472），以定义它们的功能关系。通过在整个三化螟幼虫中表达或共表达来获得蛋白质，并进行纯化。使用凝胶过滤和沉降平衡方法研究它们的相互作用。通过在模拟黑素体和 ER pH 值的条件下，在存在（1:1 和 1:20 摩尔比）或不存在 TYRP1tr 的情况下，测量酪氨酸酶二酚氧化酶活性的动力学，研究了 TYRtr 的保护。我们的数据表明，TYRtr 与过量的 TYRP1tr 孵育可保护 TYR，随着时间的推移增加其稳定性。然而，这种机制似乎不涉及形成稳定的异源寡聚复合物来维持保护功能。
