Model for the function of p12 during the early stages of retroviral replication. In addition to the late-domain, we propose that p12 carries two early domains in the N-terminus (Early-A, E-A, green box) and the C-terminus (Early-B, E-B, purple box). (A) Infection of a cell with a gammaretrovirus containing wild type p12 leads to successful integration of viral cDNA (turquoise) into the host chromatin. (B) Alterations to the N-terminal domain of p12, E-A, affect the stability of the viral core and abort infection very early in the replication pathway, sometimes inhibiting reverse transcription. The virus is therefore unable to abrogate restriction factors. (C) Alterations to the C-terminal domain of p12, E-B, do not affect the very early stages of infection and p12 is present in the PIC by virtue of interactions at the N-terminus. However, p12 is unable to tether the PIC to host chromatin and the viral cDNA cannot integrate successfully into the DNA of the host.