Kim J G, Armstrong R C, Berndt J A, Kim N W, Hudson L D
Laboratory of Developmental Neurogenetics, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, 20892-4160, USA.
Mol Cell Neurosci. 1998 Oct;12(3):119-40. doi: 10.1006/mcne.1998.0701.
Internal initiation of translation, a mechanism infrequently used by cellular messages, avoids the requirement of a methyl cap structure for translation of messenger RNAs. The mRNA transcript encoding the DNA-binding protein MYT2 represents one of the exceptional cellular messages that contains an internal ribosome entry site (IRES). The RNA pseudoknot structure located in the 5' untranslated region of MYT2 functions to promote translation in vivo. MYT2 was cloned by its specific binding to a TTCCA motif in the promoter region of a glial-specific gene, myelin proteolipid protein. MYT2 also recognizes single-stranded nucleic acids. In the central nervous system, MYT2 protein is found in oligodendrocyte progenitor cells, subsets of neurons, and cells of the choroid plexus together with ciliated ependymal cells. MYT2 protein can also be secreted from cells, an atypical event for a DNA-binding protein. The presence of an internal ribosome entry site in MYT2, together with the unusual localization of MYT2, suggests that this nucleic acid-binding protein may be in the class of proteins involved in cellular growth control and survival in the nervous system.
翻译起始的内部机制是细胞信使RNA很少使用的一种机制，它避免了信使RNA翻译对甲基化帽结构的需求。编码DNA结合蛋白MYT2的mRNA转录本是含有内部核糖体进入位点（IRES）的特殊细胞信使RNA之一。位于MYT2 5'非翻译区的RNA假结结构在体内发挥促进翻译的作用。MYT2是通过其与神经胶质特异性基因髓磷脂蛋白脂蛋白启动子区域的TTCCA基序的特异性结合而克隆得到的。MYT2也能识别单链核酸。在中枢神经系统中，MYT2蛋白存在于少突胶质前体细胞、神经元亚群以及脉络丛细胞和纤毛室管膜细胞中。MYT2蛋白也可以从细胞中分泌出来，这对DNA结合蛋白来说是不寻常的。MYT2中存在内部核糖体进入位点，以及其不寻常的定位，表明这种核酸结合蛋白可能属于参与神经系统细胞生长控制和存活的蛋白质类别。
