Arabinogalactan proteins (AGPs) are ubiquitous cell wall and plasma membrane components and are characterised by extensive glycosylation and heterogeneity of their carbohydrate and protein units. The aim of the study was to evaluate the structural features of AGPs present in apple fruits at different stages of the ripening process. AGPs were extracted using the Yariv reagent and examined using SDS-PAGE, immunoblotting, FT-IR, and AFM. In situ analysis, immunofluorescence (CLSM) and immunogold-labelling (TEM), were performed. We demonstrated that AGPs were indeed present in apple fruits at the different stages of the ripening process. The changes in the amount (1.52–2.08 mg g⁻¹), diameter (152.73–75.05 nm), molecular mass (50–250 kDa), and distribution in the cell of AGPs demonstrate their variable presence and changeable structure during the ripening process. We propose specific wavenumbers, i.e. 1265 cm⁻¹, 1117 cm⁻¹, and 960 cm⁻¹, which could be assigned to AGPs. The immunofluorescence and immunogold-labelling results indicate that the JIM13 antibody is the most characteristic for AGPs in apple fruits. This study quantitatively demonstrated for the first time that AGP accumulation occurs in ripe fruits, which is supported by the highest AGPs content, the highest molecular mass, and the appearance of a specific distribution pattern at the cellular level.

阿拉伯半乳聚糖蛋白（AGPs）是无处不在的细胞壁和质膜成分，其特征在于其糖类和蛋白质单元的广泛糖基化和异质性。该研究的目的是评估苹果果实成熟过程中不同阶段存在的AGP的结构特征。使用Yariv试剂提取AGP，并使用SDS-PAGE，免疫印迹，FT-IR和AFM进行检查。在原位分析中，进行了免疫荧光（CLSM）和免疫金标记（TEM）。我们证明了在成熟过程的不同阶段，苹果果实中确实存在AGP。量的变化（1.52-2.08 mg g ^-1），直径（152.73–75.05 nm），分子量（50–250 kDa）以及AGP在细胞中的分布表明它们在成熟过程中存在可变且结构可变。我们提出具体的波数，即1265厘米^-1，1117厘米^-1和960厘米^-1，这可能被分配到的AGP。免疫荧光和免疫金标记结果表明，JIM13抗体是苹果果实中AGP最具特征的抗体。这项研究首次定量证明了AGP积累发生在成熟果实中，这由最高的AGP含量，最高的分子质量和细胞水平上特定分布模式的出现来支持。