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Structural phosphoproteins associated with purified measles virions and cytoplasmic nucleocapsids
Abstract:
Measles virions and cytoplasmic nucleocapsids were labeled with [3H]-amino acids and [32P]-orthophosphate and were purified from infected Vero cells. When analyzed by PAGE, the two capsid-associated polypeptides (VP2 -- 69,000 daltons, VP3 -- 60,000 daltons) were shown to be phosphorylated. Characterization of the phosphorylated polypeptides by acid hydrolysis and high-voltage paper electrophoresis showed that serine was the major phosphorylated amino acid, although lesser amounts of phosphothreonine were also present. The possible role of phosphorylation in the replication cycle of the virus is discussed.
Insights
Measles virus capsid proteins VP2 and VP3 are phosphorylated, primarily on serine residues. This phosphorylation may play a role in the measles virus replication cycle.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Measles virus is a significant human pathogen.
- Understanding the molecular mechanisms of measles virus replication is crucial for developing antiviral strategies.
- Post-translational modifications, such as phosphorylation, can regulate viral protein function.
Purpose of the Study:
- To investigate the phosphorylation status of measles virus capsid proteins.
- To identify the specific amino acid residues involved in the phosphorylation of measles virus capsid proteins.
- To explore the potential role of phosphorylation in measles virus replication.
Main Methods:
- Purification of measles virions and cytoplasmic nucleocapsids from infected Vero cells.
- Labeling with [3H]-amino acids and [32P]-orthophosphate.
- Analysis of phosphorylated polypeptides using Polyacrylamide Gel Electrophoresis (PAGE).
- Characterization of phosphorylated amino acids via acid hydrolysis and high-voltage paper electrophoresis.
Main Results:
- Two measles virus capsid-associated polypeptides, VP2 (69,000 daltons) and VP3 (60,000 daltons), were identified as phosphorylated.
- Serine was determined to be the major phosphorylated amino acid in these proteins.
- Lesser amounts of phosphothreonine were also detected.
Conclusions:
- Measles virus capsid proteins VP2 and VP3 undergo phosphorylation.
- Phosphorylation occurs predominantly on serine residues, with some threonine phosphorylation also observed.
- The phosphorylation of these capsid proteins may be a regulatory mechanism influencing the measles virus replication cycle.