de Vijlder J J, Veenboer G J, van Dijk J E
Department of Experimental Pediatric Endocrinology, University of Amsterdam, The Netherlands.
Endocrinology. 1992 Aug;131(2):578-84. doi: 10.1210/endo.131.2.1639008.
Iodoalbumin has been found in the goiter of Dutch goats with a thyroglobulin synthesis defect. Immunohistochemical studies showed that in the goiter the percentage of follicles containing albumin was higher than that in normal thyroid glands. In the albumin-containing follicles of normal and goitrous glands, transferrin and immunoglobulin G could be found. Also, between the epithelial cells, serum proteins were detected. These results indicate intercellular passage of serum proteins. After in vivo labeling with 125I, goiter slices were incubated with [3H] leucine. Purified 125I-containing albumin did not contain [3H]leucine, while thyroglobulin antigens were double labeled. Cyanogen bromide treatment of albumin out of the goiter and of serum albumin gave comparable cleavage patterns, indicating that no great differences in amino acid composition, especially methionine, exist. In total RNA from goiter, no albumin mRNA could be detected after blotting and hybridization with goat albumin cDNA. Also, the polymerase chain reaction method with albumin DNA primers was unable to detect any albumin mRNA in normal and goitrous glands of goats. From these results we conclude that "thyralbumin" originates from blood and is not synthesized by the thyroid gland.
在患有甲状腺球蛋白合成缺陷的荷兰山羊的甲状腺肿中发现了碘白蛋白。免疫组织化学研究表明，甲状腺肿中含有白蛋白的滤泡百分比高于正常甲状腺。在正常和甲状腺肿腺体中含白蛋白的滤泡中，可发现转铁蛋白和免疫球蛋白G。此外，在上皮细胞之间检测到血清蛋白。这些结果表明血清蛋白可通过细胞间通道。用125I进行体内标记后，将甲状腺肿切片与[3H]亮氨酸一起孵育。纯化的含125I白蛋白不含[3H]亮氨酸，而甲状腺球蛋白抗原则被双重标记。对甲状腺肿中的白蛋白和血清白蛋白进行溴化氰处理，得到了类似的裂解模式，这表明氨基酸组成，尤其是甲硫氨酸，没有很大差异。在用山羊白蛋白cDNA进行印迹杂交后，在甲状腺肿的总RNA中未检测到白蛋白mRNA。此外，使用白蛋白DNA引物的聚合酶链反应方法也无法在山羊的正常和甲状腺肿腺体中检测到任何白蛋白mRNA。从这些结果我们得出结论，“甲状腺白蛋白”源自血液，并非由甲状腺合成。
