highly significantp < 0.0001
This represents an almost five-times enrichment for the presence of the AAAUAA motif in this set of highly expressed transcripts for storage proteins (which is highly significant, with p < 0.0001, according to the one-sided Fisher’s exact test based on a 2 × 2 contingency table) with respect to transcripts not involved in the nutrient reservoir activity (represented by a random sample of 6258 protein-coding genes whose 3′ UTR sequence is identified in rice, which showed a presence of the motif in about 20% of the 3′ UTR sequence).