SUBCELLULAR LOCALIZATION OF MELANIN BIOSYNTHESIS
SUBCELLULAR LOCALIZATION OF MELANIN BIOSYNTHESIS
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黑色素生物合成的亚细胞定位
DOI：
10.1111/j.1749-6632.1963.tb42869.x
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发表时间：
1963
影响因子：
5.2
通讯作者：
Thomas B. Fitzpatrick
中科院分区：
文献类型：
--
作者：
M. Seiji;K. Shimao;M. S. C. Birbeck;Thomas B. Fitzpatrick
在过去的四年里，对黑素细胞精细结构的研究改变了对这种细胞性质的认识。Barnicot和Birbeck 4是第一个指出黑素细胞含有类似于分泌细胞中所见的膜系统的人。此外，他们还观察到黑素细胞胞质中的黑素颗粒并不具有均匀的结构，但似乎存在于不同的发育阶段;颗粒开始为“中空的空泡，其中纤细的物质以折叠的薄片的形式出现......材料迅速变厚，并由更致密的材料沉积而形成，直到形成约为原始空泡尺寸两倍的固体。随后对黑色素颗粒6 J 4J 5 J 9的精细结构的研究证实并扩展了这些发现。在本文报道的研究中，用超离心密度梯度法从色素组织中分离出的颗粒，用生物化学技术和电子显微镜进行了检查。所获得的结果使得有可能勾勒出黑色素颗粒的发育途径。由于黑色素颗粒是一种特殊的细胞器，不仅在结构和发育方面，而且在化学和酶组成方面与线粒体不同，因此提出了一套新的术语来描述其发育的各个阶段。引入新术语的理由是，单一的、包含性的术语“黑色素颗粒”不足以精确地描述在黑化过程中颗粒中发生的结构和化学变态。在图1中已经概述了前黑素体、黑素体和黑素颗粒的基本特征：黑素细胞中发现的三种专门的细胞器。第一阶段，多肽被合成并浓缩成酶蛋白分子的二级和三级结构（“前酪氨酸”）。
Studies of the fine structure of the melanocyte have in the last four years altered the concept of the nature of this cell. Barnicot and Birbeck4 were the first to point out that melanocytes contain a system of membranes similar to those seen in secretory cells. In addition, they have observed that melanin granules in the cytoplasm of the melanocyte are not of uniform structure, but appear to exist in varying stages of development; the granules start as “hollow vacuoles in which a tenuous material appears in the form of a folded lamella... the material is rapidly thickened and defined by the deposition of more dense material, until a solid body about twice the size of the original vacuole is formed.” Subsequent studies of the fine structure of melanin granules6J4J5J9 have confirmed and extended these findings. In the study reported here, the particles isolated from pigmented tissues by ultracentrifugal, density-gradient methods have been examined by both biochemical techniques and electronmicroscopy. The results obtained have made it possible to outline a pathway of development of melanin granules. Because melanin granules are specialized organelles which differ from mitochondria not only in structure and development, but also in chemical and enzymic composition, a set of new terms is proposed for the various stages of their development. Justification for this introduction of new terms is the inadequacy of the single, inclusive term,“melanin granule,” to describe with precision the structural and chemical metamorphoses which take place in the granule during melanization. In FIGURE 1 have been outlined the essential features of premelanosomes, melanosomes, and melanin granules: the three specialized organelles found in melanocytes.It is believed that three stages can be recognized in the formation of the melanin granule: the final product of the melanocyte (FIGURE 1): I. A first stage in which polypeptides are synthesized and condensed into the secondary and tertiary structures (“pro-tyrosinme”) of the enzymic protein molecules.