Fig. 2From: The emerging role of the piRNA/PIWI complex in respiratory tract diseasesThe ping-pong cycle. The antisense piRNA (5ʹ-3ʹ) binding with the Aub protein cuts the transcript of the transposon mRNA to produce sense piRNA (3ʹ-5ʹ). Then, the sense piRNA (3ʹ-5ʹ) binds with the AGO3 protein and becomes mature sense piRNAs through shear and methylation in in a similar manner. The mature sense piRNAs (3ʹ-5ʹ) combine with the piRNA cluster transcript and sliced it to produce antisense piRNA (5ʹ-3ʹ), which is repeated in the ping-pong cycle. The piRNA produced in the ping-pong cycle is also called secondary piRNABack to article page