A protein from Ficus elastica rubber particles is related to proteins from Hevea brasiliensis and Parthenium argentatum

Rubber particles, having high rubber transferase (RuT) activity, were isolated from Ficus elastica latex. The predominant protein in these rubber particles is a large hydrophobic glycoprotein (termed LPR for large protein from rubber particles), with an apparent monomeric Mr of 376 000 on SDS-PAGE. A Mr of 750 000 was determined with native PAGE, indicating that LPR probably exists as a dimer. Antibodies raised to purified LPR recognized blotted intact F. elastica rubber particles, as well as LPR, demonstrating that LPR is situated at or near the surface of the particles. Anti-LPR antibodies also recognized enzymatically active rubber particles and rubber particle proteins from two other rubber-producing plants, Hevea brasiliensis and Parthenium argentatum. This indicates that the rubber particles of all three rubber-producing species contain proteins with common antigenic determinants. Large proteins, similar in size to LPR, were found in preparations of rubber particles from H. brasiliensis and P. argentatum. These results are the first demonstration that rubber particles from different species contain similar proteins that may share common functions in rubber biosynthesis and/or rubber particle structure.