IDENTIFICATION OF PARTHENIUM-ARGENTATUM RUBBER PARTICLE PROTEINS IMMUNOPRECIPITATED BY AN ANTIBODY THAT SPECIFICALLY INHIBITS RUBBER TRANSFERASE-ACTIVITY

We have shown that an antibody raised to LPR (M(r) 367 000) the predominant protein on Ficus elastica rubber particles, recognized three proteins from Parthenium argentatum (guayule) rubber particles, the glycoprotein RPP (M(r) 52 000), and two smaller proteins (M(r) 15 000 and 9000). Since anti-LPR IgG specifically inhibited the rubber particle-bound cis-prenyl transferase (rubber transferase) in both F. elastica and P. argentatum, our results indicate that these proteins probably play roles in rubber transferase activity. Although LPR and RPP differ considerably in size, we show that RPP can form a large protein complex. A M(r) of 450 000 was determined by electrophoresis under nondenaturing conditions. Thus rubber transferase activity appears to be associated with large proteins in both F. elastica and P. argentatum.