Fig. 3.

H-F111A homodimers are structurally distinct from homodimers of unmodified H or other H-complementation groups. (A) Native-PAGE analysis of digitonin-extracted H tetramers reveals that H-F111A homodimers are unable to heterotetramerize with any other H homodimer species. To distinguish better untagged and size-tagged H oligomers in native-PAGE, size-increased H constructs contained a tandem copy of the tag H_XXL. The migration positions of size-tagged H homo- and heterotetramers are shown. (B) H homotetramers harboring stalk mutations that prevent interaction with F (F111A, L114A, I118A, or 110-114A) show a distinct migration pattern in native gels. The predominant H tetramer migration profiles of standard H, H-I98A, and H-ΔCD46 (gray marker) and H-F111A (black marker) are shown.