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Structure of the mouse mammary tumor virus: polypeptides and glycoproteins
Abstract:
The polypeptide and glycoprotein compositions of the mouse mammary tumor virus virion from primary monolayer cultures of BALB/cfC3H mouse mammary tumor cells were studied by polyacrylamide gel electrophoresis by using internal and external labeling and Coomassie blue and periodic acid Schiff (PAS) staining. Twelve polypeptides were reproducibly resolved by the combined methods. Five major polypeptides were demonstrable with estimated molecular weights of 52,000, 36,000, 28,000, 14,000, and 10,000. Seven minor polypeptides were also consistently detected and had estimated molecular weights of 70,000, 60,000, 46,000, 38,000, 30,000, 22,000, and 17,000. Carbohydrate was associated with five of these polypeptides as measured by PAS stain or [(3)H] glucosamine labeling, or both. These glycoproteins had estimated molecular weights of 70,000, 60,000, 52,000, 36,000 and 10,000. The majority of the PAS stain and glucosamine was found in the 52,000 and 36,000 dalton peaks.
Insights
This study characterized mouse mammary tumor virus (MMTV) virion proteins using gel electrophoresis. Researchers identified twelve polypeptides, including five major ones, and five glycoproteins, with specific molecular weights.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Mouse mammary tumor virus (MMTV) is a retrovirus associated with mammary cancer in mice.
- Understanding the protein and glycoprotein composition of MMTV virions is crucial for studying its structure and function.
Purpose of the Study:
- To analyze the polypeptide and glycoprotein composition of the MMTV virion.
- To identify and characterize the molecular weights of viral proteins and glycoproteins.
Main Methods:
- Polyacrylamide gel electrophoresis was employed for protein separation.
- Internal and external labeling techniques were used.
- Coomassie blue and periodic acid Schiff (PAS) staining identified proteins and carbohydrates, respectively.
- Radioactive glucosamine labeling confirmed glycoprotein presence.
Main Results:
- Twelve distinct polypeptides were resolved in the MMTV virion.
- Five major polypeptides with molecular weights of 52,000, 36,000, 28,000, 14,000, and 10,000 were identified.
- Seven minor polypeptides were also detected, ranging from 17,000 to 70,000 molecular weight.
- Five glycoproteins were identified, with major carbohydrate content in the 52,000 and 36,000 dalton polypeptides.
Conclusions:
- The study provides a detailed characterization of the MMTV virion's protein and glycoprotein components.
- The identified glycoproteins, particularly those at 52,000 and 36,000 daltons, are significant components of the MMTV virion structure.