Abstract
Rice α-amylaseI-1 (AmyI-1) is a glycoprotein bearing N-linked carbohydrate chain, that is secreted from the secretory tissues. We have recently demonstrated thatα-amylaseI-1 was localized inside of plastids in rice leaf cells. To clarify targeting mechanism of α-amylaseI-1 to plastids, transient expression analyses of α-amylaseI-1 fused with GFP were performed in onion epidermal cells. Simultaneous expression of AmyI-1-GFP and plastid marker (WxTP-DsRed) indicated that AmyI-1-GFP co-localized with the plastid marker. Furthermore, the targeting of AmyI-1-GFP into plastids was arrested by the dominant negative mutants of AtArf1 and AtSar1 those are involved in the traffic of ER-to-Golgi. In addition, when expression of Golgi marker (ST-mRFP) and WxTP-GFP with or without overexpression of AmyI-1 was carried out, incorporation of ST-mRFP to WxTP-GFP frequently occurred under overexpression AmyI-1. Based on the overall experimental results, we concluded that α-amylaseI-1 targets into the plastids through the ER-Golgi system.
