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Processing of pseudorabies virus glycoprotein gII
U Wölfer1, V Kruft, D Sawitzky
1Institut für Klinische und Experimentelle Virologie der Freien Universität Berlin, Federal Republic of Germany.
Abstract:
The glycoprotein complex gII of pseudorabies virus was isolated by immunoprecipitation with the monoclonal antibody M5, which was covalently linked to protein A-Sepharose. After sodium dodecyl sulfate-polyarylamide gel electrophoresis under reducing conditions and blotting onto poly(vinylidene difluoride) membrane, its subunits, gIIa, gIIb, and gIIc, were subjected to N-terminal sequencing. gIIa and gIIb start at position 59 and gIIc starts at position 503 according to the amino acid sequence deduced from the gene, indicating that there is one major protein (gIIa) which is cleaved into the two protein fragments gIIb and gIIc. Protein labeling with 14C-amino acids gave no indication that the three proteins (gIIa, gIIb, and gIIc) of the complex are present in equimolar ratios. It seems that gIIa is only a minor component of the complex, whereas gIIb and gIIc are contained in equimolar amounts.
Insights
The pseudorabies virus glycoprotein complex gII, composed of subunits gIIa, gIIb, and gIIc, was analyzed. Results indicate gIIa is a minor component, while gIIb and gIIc are equimolar fragments derived from gIIa.
Area of Science:
- Virology
- Molecular Biology
- Protein Chemistry
Background:
- The pseudorabies virus (PRV) glycoprotein complex gII is crucial for viral infection.
- Understanding the subunit composition and processing of gII is essential for viral pathogenesis research.
Purpose of the Study:
- To elucidate the subunit composition and processing of the PRV glycoprotein complex gII.
- To determine the N-terminal sequences and relative stoichiometry of gII subunits.
Main Methods:
- Immunoprecipitation of PRV gII using monoclonal antibody M5 and protein A-Sepharose.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions.
- N-terminal sequencing of isolated subunits and protein labeling with 14C-amino acids.
Main Results:
- The glycoprotein complex gII consists of subunits gIIa, gIIb, and gIIc.
- N-terminal sequencing revealed gIIa and gIIb share a common start site (position 59), while gIIc starts later (position 503).
- Protein labeling indicated gIIa is a minor component, whereas gIIb and gIIc are present in equimolar amounts, suggesting gIIa is cleaved into gIIb and gIIc.
Conclusions:
- The PRV glycoprotein gII undergoes post-translational cleavage.
- Subunits gIIb and gIIc represent equimolar fragments derived from a larger precursor, likely initiated as gIIa.
- The stoichiometry suggests a specific processing pathway for the PRV gII complex.