A secreted DNA-binding protein that is translated through an internal ribosome entry site (IRES) and distributed in a...

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.