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Here , we present evidence for a model in which mRNA sequences up to around 100 nucleotides downstream from the start codon of 21K fold back and base - pair to the 21K translation initiation region , thereby decreasing the translation initiation frequency .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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