FIGURE 3.

Identification of a functional core domain of the ssSPTs. A, Lcb1Δlcb2Δtsc3Δ mutant yeast expressing the indicated HA-ssSPTa (left) and HA-ssSPTb (right) mutant proteins along with hLCB1and hLCB2a were tested for growth at 26 °C or 37 °C or with PHS. B, SPT activities with either C16- or C18-CoA as substrate were measured using microsomes prepared from cells expressing the wild-type and N-, C-, or doubly truncated ssSPTa (left) or ssSPTb (right) proteins as described under “Experimental Procedures.” C, expression of the truncated HA-ssSPTa mutant (left) or HA-ssSPTb mutant (right) subunits was assessed by immunoblotting with anti-HA.