Model for possible role of nonautonomous type IAP protein. (A) IAP particle formation mediated by IΔ1 type IAP protein. Transcript of IΔ1 type IAP element is bound by IΔ1 type IAP protein immediately after translation. The full-length type autonomous IAP protein is recruited to the RNA–protein complex through interaction between IΔ1 type and full-length type IAP proteins, leading to the formation of transposition competent IAP particle. (B) Inefficient formation of IAP particle in the absence of IΔ1 type IAP protein. Accessibility of full-length type autonomous IAP protein to IΔ1 type IAP transcript is impaired due to the lack of IΔ1 type IAP protein. Note that the conformation of the IΔ1 type IAP protein in the IAP particle is unknown and only schematically drawn here.
