FIG. 4.

Interaction of the HIV-1, SIV, and HTLV-1 TM-CD Tyr-based motifs with μ1 and μ2 subunits in the yeast two-hybrid system. The yeast reporter strain L40 was cotransformed with plasmids encoding various Gal4 AD-adaptin hybrids and plasmids encoding the LexA BD fused to TM-CD707-726 of HIV-1 LAI (A), TM-CD716-733 of SIVmac239 (B), or complete TM-CD of HTLV-1 (C). Cotransformants were analyzed for histidine auxotrophy. They were patched on medium with histidine (+His) and then replica plated on medium without histidine (−His). Growth in the absence of histidine indicates interaction between hybrid proteins. The positive control was the interaction between Ras and Raf proteins, which bind to each other efficiently (lanes 9). Binding specificity was verified by the absence of interaction between the retroviral tyrosine-based motifs TM-CD and the Gal4 AD alone (A and B, lanes 8).