The C2 domain of Rsp5 binds to the C terminus of Sec7. A,
yeast two-hybrid analysis of the interaction between the C terminus of Sec7
(aa 1836–2009) and the wild-type or 3K→Q mutant C2 domain. Yeast
strains carrying the indicated activation and binding domain plasmids were
incubated on minimal medium at 30 °C. B, lysates prepared from
bacteria expressing GST-C2 or GST-C23K→Q were incubated with
immobilized His6-Sec71836-2009. Bound proteins were
eluted by boiling, resolved by SDS-PAGE, and analyzed by immunoblotting with
GST antibodies. His6-Rvs167SH3 was used as a control for
nonspecific binding. The presence of equal amounts of immobilized protein in
each reaction was verified by Coomassie staining of the eluted, resolved
proteins (not shown). C, proteins from yeast cell lysates containing
Sec7-GFP (LHY5440) and untagged Sec7 (LHY1850) were immunoprecipitated using
GFP antibodies. Total lysates (0.7%, anti-GFP blot and 0.07%, anti-Rsp5 blot)
and precipitated proteins were resolved by SDS-PAGE and analyzed by
immunoblotting (IB) with GFP or Rsp5 antibodies. IP,
immunoprecipitates.