The protein farnesyltransferase purified from rat brain contains two nonidentical subunits, α and β. The holoenzyme forms a stable complex with [3H]farnesyl pyrophosphate (FPP) that can be isolated by gel filtration. The [3H]FPP is not covalently bound to the enzyme; it is released unaltered when the enzyme is denatured. When incubated with an acceptor such as p21(H-ras), the complex transfers [3H]farnesyl from the bound [3H]FPP to the ras protein. This transfer is not sensitive to dilution by unbound FPP, suggesting that the [3H]FPP is bound at a site that leads to direct transfer to the p21(H-ras) acceptor. Cross-linking studies show that the p21(H-ras) binds to the lower molecular weight subunit (β-subunit), raising the possibility that the [3H]FPP binds to the α-subunit. If this suggestion can be confirmed, it would invoke a reaction mechanism in which the α-subunit acts as a prenyl pyrophosphate carrier that delivers FPP to p21(H-ras) which is bound to the β-subunit.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - Aug 16 1991|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology