An S47A or S48A mutation within the 1-100-aa per protein fragment inhibits (but does not completely abolish) binding, the S47A mutation more strongly than the S48A mutation.
Head extracts prepared from flies expressing wild-type and mutant variants of HA-tagged per; dPER(S44-48A) = all 4 serine residues in aa 44-48 (SSGSS) substituted with alanine.
Binding with dPER(S44-48A) variant very low, but not abolished entirely.
