Figure 1. Mechanisms of recruitment of the Ago1/Smaug complex. (A) The standard mechanism of Ago1 recruitment to an mRNA via the complementarity between a bound miRNA and the target. (B) The model for the Smaug-dependent miRNA-independent recruitment of Ago1 to mRNAs such as nos through Smaug’s interaction with an SRE stem/loop. Note that, as discussed in more detail in the text, Ago1 in this complex may contain an associated miRNA which, while not base paired with the target mRNA and therefore not involved in Ago1 recruitment, could be important for translational repression. (C) The Ago1/Smaug complex could be recruited to some mRNAs through base pairing between a miRNA and the transcript. (D) The Ago1/Smaug complex could be recruited to other mRNAs through the combined interaction of Smaug with an SRE and the complementarity of a miRNA to the transcript.