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Processing of p60v-src to its myristylated membrane-bound form
Molecular and Cellular Biology
|October 1, 1985
Summary
Myristoylation of Rous sarcoma virus p60src protein is crucial for its membrane association and cell transformation. This lipid modification occurs before membrane binding and is required for stable plasma membrane association.
Area of Science:
- Molecular Biology
- Virology
- Cell Biology
Background:
- p60src protein from Rous sarcoma virus is myristoylated at its N-terminal glycine residue.
- Myristoylation is essential for p60src membrane association and cell transformation.
- Previous studies utilized src mutants with alterations in the N-terminal 30 kilodaltons.
Purpose of the Study:
- To analyze the process of p60src myristoylation in wild-type and mutant-infected cells.
- To investigate the relationship between initiator methionine removal and myristoylation.
- To determine the role of myristoylation in p60src membrane association and interaction with cellular proteins.
Main Methods:
- Analysis of myristoylated src proteins in wild-type and mutant Rous sarcoma virus-infected cells.
- Kinetics studies of myristoylation and p60src association with p50 and p90 proteins.
- Examination of src mutants with specific deletions (e.g., amino acids 169-264) and N-terminal deletions.
Main Results:
- Removal of the initiator methionine is not obligatorily coupled with myristoylation.
- Myristoylation precedes membrane association of p60src.
- Transient association with p50 and p90 occurs independently of myristoylation.
- Myristoylation is necessary but not sufficient for stable plasma membrane association.
- A specific src deletion mutant (169-264) is myristoylated, membrane-unbound, transformation-defective, and stably associated with p50/p90.
- N-terminal deletion mutants with tyrosine kinase activity can be myristoylated and membrane-bound but show reduced transformation activity.
Conclusions:
- Myristoylation is a critical step for p60src membrane localization and function.
- Additional N-terminal domains beyond the myristoylation site are involved in full cell transformation.
- The N-terminal region of p60src contains multiple functional domains regulating its activity and localization.
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