The composition of seed storage proteins (SSPs) in olive endosperm and cotyledon has beenanalyzed. Precursor forms of these proteins are made up of individual proteins, which have beenpurified to homogeneity and further named p1-p5 (20.5, 21.5, 25.5, 27.5, and 30 kDa, respectively).N-terminal sequences of p1 and p2 proteins displayed relevant homology to the basic subunit of the11
S family of plant SSPs (legumins). Two-dimensional polyacrylamide gel electrophoresis experimentsallowed us to verify the basic character of p1 and p2 and the acidic character of p3, p4, and p5proteins. In
addition, the putative presence of highly similar isoforms or posttranslational modificationsof these polypeptides was detected. As a result, a model describing the putative association of p1-p5 proteins into subunits of
![](/images/gifchars/alpha.gif)
(acidic)/
![](/images/gifchars/beta2.gif)
(basic) type has been proposed. Solubility experiments haveshown that the majority of these olive seed proteins from the 11
S storage protein family are extractedwith aqueous alcohol and only partially with water and diluted saline solutions, therefore suggestingtheir similarity to prolamines. Moreover, no visible differences were found in either subunit compositionor 11
S proteins mass among six olive cultivars examined. This result suggests that the synthesis ofstorage proteins is highly conserved in this plant species. By using a rabbit antiserum raised to p1protein, the proteins have also been immunolocalized in olive seed tissues, showing that theyaccumulate in conspicuous protein bodies present in both the endosperm and the cotyledon.Keywords: Cotyledon; endosperm;
Olea europaea L.; olive tree; protein bodies; 11
S storage protein