苹果果实组织脱落酸结合位点的亚细胞定位

Subcellular Localization of ABA Binding Sites in Tissues of Apple 

在苹果（ＭａｌｕｓｐｕｍｉｌａＭｉｌ）果实细胞的可溶性组分中存在ＡＢＡ特异结合位点，这些位点能与ＡＢＡ形成稳定的３ＨＡＢＡ蛋白结合复合物，而微粒体部分未表现出３ＨＡＢＡ结合活性。可溶性组分对３ＨＡＢＡ的结合效率与结合稳定性需要活体组织完整细胞的存在。ＡＢＡ共价交联物ＡＢＡＬＹＣＨ，具有与ＡＢＡ相同的抑制红苋菜（ＡｍａｒａｎｔｈｕｓｔｒｉｃｏｌｏｒＬ．）种子萌发的生物活性，能有效地竞争抑制果实组织圆片对３ＨＡＢＡ的结合。通过ＡＢＡＬＹＣＨ对苹果果实组织圆片及果实组织游离细胞的荧光染色表明，未成熟果实的细胞外周被特异性地染色。在ＢＳＡ存在的情况下，ＡＢＡＬＹＣＨ复合物被转运进细胞，形成密集的强烈荧光团。结果表明，ＡＢＡＬＹＣＨ与３ＨＡＢＡ的竞争性结合发生在细胞质膜水平。

The different subcellular fractions of apple ( Malus pumila Mill) fruit were separated with differential centrifugation, and the distribution of ABA binding activities in the subcellular fractions was determined. Both the in vivo and in vitro ABA binding assayed indicated that the ABA binding sites which were detectable only in the subcellular fractions obtained from the fruit tissues fed with 3H ABA, were situated in the soluble fractions of the fruit cells. These sites could form a stable complex with ABA. The lucifer yellow CH linked ABA (ABA LYCH) which was shown to inhibit the germination of red amaranth ( Amaranthus tricolor L.) seeds as effectively as ABA, also inhibited the in vivo ABA binding in tissues of apple fruit. ABA LYCH could specifically stain the out sphere of the cells in tissue or that of the macerated cells of unripe apple fruit. With the presence of BSA, the ABA linkage complex could be transported into the cells across the plasma membrane and intensively aggregated in the places of cell contact. The results suggest that there exists a carrier of ABA localized on plasmalemma, which transports ABA across the plasma membranes before the ABA is bound at the ABA binding sites situated in the cytoplasm.