Figure 5.

Schematic representation of yeast (y) and human (h) β2 subunits and their propeptides. Secondary structure elements, helices (H), and sheets (S) are numbered. (A) The full-length hβ2c (green) and hβ2i (pink) subunits cannot substitute the endogenous yβ2 subunit (gray), neither with their natural propeptides (pp; colored) nor with the yβ2 one (gray) (for details, see the experimental procedures). Strikingly, the human β2c subunit can replace the yeast counterpart when featuring the single-point mutation S171G.¹⁹ (B) Schematic illustration of human–yeast chimeric β2i constructs according to panel (A). Sequences highlighted in pink were taken from human β2i, whereas the gray ones originate from the yeast β2 entity. All tested variants, except for the construct encoding the residues 1–53 from human β2i, caused lethality when expressed in a pup1Δ yeast strain.