Figure 6.
Gbp2 and Hrb1 might help to transmit the Upf1-mediated PTC alert to the 5ʹ-end of the mRNA. (A) Gbp2 and (B) Hrb1 interact with each other and themselves. Co-IPs of differently tagged and untagged Gbp2 and Hrb1 versions upon RNase treatment are shown. Hem15 served as a negative control. Gbp2-GFP was not always detectable in the lysates. The asterisks indicate Gbp2 bands. (C) Gbp2 and Hrb1 interact with eIF4E and eIF4G. Co-IP of Gbp2 and Hrb1 with GFP tagged versions of the 5ʹ mRNA-binding proteins is shown. The asterisks indicate Hrb1 (top) and Gbp2 (bottom) bands. (D) The Upf1 interaction with eIF4G is significantly reduced in gbp2∆ hrb1∆ upon RNase treatment. Co-IP of Upf1 with eIF4G is shown in the indicated strains. pPGAL1:CBP80PTC was induced for 2 h. All cells express pUPF1-HA. (E) Quantification of IP experiments shown in (D). Signal intensities of the Upf1-HA bands were related to the corresponding eIF4G-GFP pull-down signals. Upf1-HA signals without RNase treatment were quantified using less-exposed figures than shown in Fig. 6D. No RNase n = 5, + RNase n = 3. See also Fig S6