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An interaction between p21ras and heat shock protein hsp60, a chaperonin
1Whitehead Institute for Biomedical Research, Cambridge, MA 02142.
Abstract:
Ras proteins play a crucial role in the development of neoplasia and in signal transduction in normal cells. In a search for proteins interacting with p21ras, we previously identified a protein of 60 kDa (p60) through use of a chemical cross-linker. Using information from partial amino acid sequencing of the purified protein, we isolated full-length cDNA clones encoding this 60-kDa protein. Nucleotide sequence analysis revealed that p60 is the murine heat shock protein hsp60, a chaperonin. Association of hsp60 with p21ras appears physiological, as the amount of hsp60 complexed to p21ras was similar even in cells over-expressing p21ras, and reversing the order of cross-linking and lysis of the cells, which releases large amounts of hsp60 from mitochondria, did not alter the amount of hsp60 cross-linked to p21ras.
Insights
Researchers identified heat shock protein 60 (hsp60) as a protein that interacts with Ras proteins (p21ras). This interaction appears physiological and is crucial for understanding cellular signaling and neoplasia development.
Area of Science:
- Molecular Biology
- Cellular Biology
- Oncology
Background:
- Ras proteins are critical in cell signaling and cancer development.
- Identifying interacting proteins of Ras is key to understanding its function.
Purpose of the Study:
- To identify proteins that interact with p21ras.
- To characterize the nature of the interaction between p21ras and its binding partners.
Main Methods:
- Used chemical cross-linking to identify interacting proteins.
- Purified the 60 kDa protein (p60) and performed partial amino acid sequencing.
- Isolated full-length cDNA clones for p60.
- Analyzed nucleotide sequences.
- Performed cell lysis and cross-linking experiments under varying conditions.
Main Results:
- A 60 kDa protein (p60) was identified as interacting with p21ras.
- Sequence analysis revealed p60 to be murine heat shock protein 60 (hsp60), a chaperonin.
- The association between hsp60 and p21ras was confirmed as physiological.
- The amount of hsp60 complexed to p21ras remained consistent even in cells over-expressing p21ras.
- Cell lysis and cross-linking order did not affect the hsp60-p21ras complex levels.
Conclusions:
- Murine heat shock protein 60 (hsp60) physically associates with p21ras.
- This interaction is physiological and occurs independently of p21ras expression levels.
- Hsp60 may play a role in Ras-mediated signal transduction pathways.