Mezzetti G, Moruzzi M, Barbiroli B
Biochem J. 1984 Apr 1;219(1):99-106. doi: 10.1042/bj2190099.
The post-ribosomal fraction of chick duodenal mucosa contains Met-tRNAMetf-binding protein(s) that behaves like the eukaryotic initiation factor (eIF-2) in protein synthesis. The binding activity of cytosol protein can be measured by retention of the radioactive complex formed on a nitrocellulose membrane. Complex-formation requires Met-tRNAMetf and GTP or guanosine [beta, gamma-methylene] triphosphate, and is inhibited by aurintricarboxylic acid. The ternary initiation complex thus formed can bind to ribosomal particles from chick intestine. By sucrose-density-gradient centrifugation, [35S]Met-tRNAMetf was found to bind exclusively to 40S and not to 60S ribosomal subunit particles. In the duodenal mucosa of rachitic chicks the ability of the cytosol proteins to promote the binding of Met-tRNAMetf to ribosomal particles via ternary-complex formation is detectably increased by 3 h after injection of 1 alpha,25-dihydroxycholecalciferol, the active form of vitamin D. Cholecalciferol and ergocalciferol under the same experimental conditions failed to stimulate Met-tRNAMetf-binding activity.
鸡十二指肠黏膜的核糖体后组分含有甲硫氨酰 - tRNAfMet结合蛋白，其在蛋白质合成中表现得像真核起始因子（eIF - 2）。胞质溶胶蛋白的结合活性可以通过在硝酸纤维素膜上形成的放射性复合物的保留来测量。复合物的形成需要甲硫氨酰 - tRNAfMet和GTP或鸟苷[β,γ - 亚甲基]三磷酸，并且受到金精三羧酸的抑制。这样形成的三元起始复合物可以与鸡肠道的核糖体颗粒结合。通过蔗糖密度梯度离心，发现[35S]甲硫氨酰 - tRNAfMet仅与40S核糖体亚基颗粒结合，而不与60S核糖体亚基颗粒结合。在佝偻病雏鸡的十二指肠黏膜中，注射维生素D的活性形式1α,25 - 二羟胆钙化醇3小时后，胞质溶胶蛋白通过三元复合物形成促进甲硫氨酰 - tRNAfMet与核糖体颗粒结合的能力可检测到增加。在相同实验条件下，胆钙化醇和麦角钙化醇未能刺激甲硫氨酰 - tRNAfMet结合活性。
