Abstract
The Small Acidic Protein 1 (SMAP1) gene was identified as the regulator for the 2,4-D response in Arabidopsis root. SMAP1 has the conserved phenylalanine and aspartate rich domain (F/D). Its orthologous genes are highly conserved in plants and animals, suggesting SMAP1 has significant biological functions. To investigate the functions of SMAP1, SMAP1-GFP or SMAP1 ΔF/D-GFP were introduced to the aar1 mutant that is deficient in the SMAP1 gene. SMAP1-GFP recovered 2,4-D sensitivity of the aar1 mutant while SMAP1 ΔF/D-GFP did not, implying that F/D region is required for the SMAP1 functions. Next, using anti-GFP-MicroBeads, the proteins, which form complexes with SMAP1-GFP but not with SMAP1 ΔF/D-GFP, were pulled down and analyzed by MS. The result indicated that SMAP1-GFP binds to COP9 signalosome (CSN). The results implied that SMAP1 regulates 2,4-D response by interacting to CSN through F/D region.
