Figure 2.

PP2A A Subunit Expression in Wild-Type and Mutant Plants.

(A) Each A subunit mutant lacks expression of one A subunit protein. Protein extracts were isolated from dark-grown wild-type and mutant seedlings and subjected to immunoblot analysis using antisera raised against RCN1 protein (see Methods). Ws is the parental wild-type for the rcn1 mutant, whereas Columbia (Col) is the parent of the pp2aa2-1 and pp2aa3-1 mutants.

(B) Independent T-DNA insertion alleles exhibit matching protein expression patterns. Protein extracts were isolated from shoots (H) and roots (R) of dark-grown seedlings of the genotypes indicated and analyzed by immunoblotting with anti-RCN1 (top half) and anti-C subunit (bottom half) antisera.

(C) Seedling roots are enriched for PP2A subunits. Protein extracts were isolated from hypocotyls (H), cotyledons plus leaves (L), and roots (R) of light-grown seedlings (left) and from shoots (H) and roots (R) of dark-grown seedlings (right) of the genotypes indicated and analyzed by immunoblotting as described above. Equal amounts of total protein were loaded in each gel lane.

(D) All three A subunit proteins are detected in different organs of adult plants. Organs were harvested from adult wild-type plants, and protein extracts were isolated and analyzed as described above. Rosette, whole rosettes; silique (e), 5- to 7-mm green siliques; silique (l), 7- to 10-mm green siliques.

(E) Mutations in A subunit genes do not alter expression patterns of the remaining A subunits. Organs were harvested from adult plants of the genotypes indicated, and protein extracts were isolated and analyzed as described above. +, Ws rosette leaf extract (loading/blotting control).