Upon centrifugation, rubber latex is divided into a layer of rubber particles, the cytosol, and the lutoid-body fraction, which is of vacuolar origin. One of the proteins isolated from the lutoid-body fraction is a protein with a molecular mass of 43 kDa, which has esterase activity on p-nitrophenylpalmitate and which shows significant sequence similarity with patatin, a vacuolar protein with esterase activity from potato (Solanum tuberosum). This protein is a major allergen in rubber latex products (Hev b 7) and can also be isolated from the cytosol fraction of rubber latex. The mature protein isolated from lutoid-bodies has no structural features expected for a vacuolar protein: the N-terminal methionine in the cDNA-derived sequence is cleaved off, the second residue is N-acetylated, and the C-terminal sequence is identical to that in the cDNA-derived sequence. Thus the patatin-like protein in Hevea brasiliensis is not a vacuolar protein, but may be associated with not yet characterized particles in the cytoplasm, which either sediment with lutoid-bodies or remain in the cytosol fraction, depending on the centrifugation conditions.