Abstract
To characterize the molecular function of OsPti1a in disease resistance, we investigated the localization of OsPti1a in rice cultured cells. OsPti1a was mainly localized in plasma membrane (PM), especially to detergent resistant membranes (DRMs) that were involved in regulation of signal transduction. OsPti1a in microsomal fraction including DRMs was phosphorylated, suggesting that OsPti1a functions on the PM through protein kinase cascade. HAstrepII-tagged OsPti1a at the N-terminal did not complement ospti1a mutant phenotype. Because N-terminus of OsPti1a has a putative lipid modification site that is important for binding with PM, we investigated whether N-terminal of OsPti1a is important for its cellular localization. In contrast to wild type protein, N-terminal deleted OsPti1a was localized in the cytosol fraction. These results suggest that the localization of OsPti1a in PM is important for negative regulation of defense signaling in rice. Additionally, OsPti1a was detected in the large complex about 250-450 kDa in microsomal fraction, suggesting that OsPti1a functions in the PM-associated complex in disease resistance.
