The mRNA transcript that encodes the BtuB protein begins with a massive leader of 240 noncoding nucleotides, and its extraordinary length was our first clue that it might have an unusual function.

• 在这种蛋白质的mRNA转录子前端，有一段240个核苷酸长的先导序列，这麽长的序列暗示了它可能具有不寻常的功能。