Figure 5.
SKB1 Methylates the U snRNP Core Component LSM4.
(A) Immunoblot analysis of Arg symmetric dimethylation modification with the SYM11 antibody in response to salt stress and ABA treatments. Total protein was extracted from 11-d-old wild-type (Col-0) or skb1-1 seedlings treated with 200 mM for 6 h or 100 μM ABA for 3 h. The experiment was performed independently three times with similar results.
(B) Total protein from wild-type seedlings treated with ABA for 5 h was immunoprecipitated with SYM11. Protein bands (7 to 17 kD) were identified by mass spectrometry and are indicated at the right.
(C) and (E) In vitro methylation assay. GST-SM or GST-LSM proteins and GST-SKB1 were purified from E. coli and incubated in the presence of [3H]-SAM. Methylated proteins were monitored by autoradiography.
(D) Full-length protein sequence of Arabidopsis LSM4, the location of three RG boxes, and the truncations in LSM4 (d1), LSM4 (d2), and LSM4 (d3).