Fig. 6. Summary of AS1-AS2 suppression tests.

A) Positive suppression pairs. Horizontal arrows at the top point away from the helix with a starting null lesion and toward the targeted helix. Thick vertical lines next to some amino acid replacements at suppressor residues indicate several different changes that suppressed the same null defect.

B) Negative suppression tests involving suppressible null alleles. This diagram indicates targeted residues that did not give rise to suppressors of null defects known to be suppressible from the tests in (A). Not all combinations of null and target residues were tested. Gray circles indicate previously-suppressible null alleles; open circles indicated targeted residues that yielded no suppressors.

C) Negative suppression tests of other null alleles. This diagram summarizes combinations of null defects and targeted residues that did not give rise to suppression effects. Not all combinations of null and target residues were tested. Thick vertical gray lines group multiple null lesions tested at some residues.