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Updated: Jul 11, 2026
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Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution
Published on: January 16, 2017
Ras (CXXX) and Rab (CC/CXC) prenylation signal sequences are unique and functionally distinct
R Khosravi-Far1, G J Clark, K Abe
1Department of Pharmacology, Lineberger Cancer Center, University of North Carolina, Chapel Hill 27599.
The Journal of Biological Chemistry
|December 5, 1992
Summary
Rab proteins require complex sequences, not just CC/CXC motifs, for isoprenoid modification. A shared geranylgeranyl transferase modifies Rab proteins, suggesting conformational recognition is key.
Area of Science:
- Molecular Biology
- Protein Modification
- Cellular Signaling
Background:
- Rab proteins are crucial for intracellular transport.
- Isoprenoid modification is essential for the function of many proteins, including Ras.
- Rab proteins utilize CC or CXC terminal motifs, unlike the CXXX motif in Ras.
Purpose of the Study:
- To investigate the sequence requirements for Rab protein isoprenoid modification.
- To compare the functional relationship between Ras CXXX and Rab CC/CXC motifs.
- To determine if Rab CC/CXC motifs can substitute for the Ras CXXX motif in signaling isoprenoid modification.
Main Methods:
- Generation of chimeric Ras proteins with Rab carboxyl-terminal sequences.
- In vitro and in vivo isoprenylation assays.
- Competition studies using geranylgeranyl transferase.
Main Results:
- Chimeric Ras proteins with Rab CC/CXC motifs were not isoprenylated.
- Extended Rab carboxyl-terminal sequences in chimeric proteins also failed to induce isoprenylation.
- Competition assays confirmed a common geranylgeranyl transferase activity for Rab proteins.
Conclusions:
- Rab protein isoprenoid modification is more complex than the Ras CXXX motif.
- Rab geranylgeranyl transferase likely recognizes protein conformation for modification.
- A single geranylgeranyl transferase activity modifies Rab proteins with CC or CXC motifs.
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