Murine leukemia virus (T-8)-transformed cells: identification of a precursor polyprotein containing gag gene-coded...

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Mink cell focus-inducing virus (MCFV) is a type C retrovirus.
• Nonproductive transformation of cells by MCFV leads to expression of specific viral proteins.
• Previous studies indicated precursor polyproteins in cells transformed by other mammalian sarcoma viruses.

Purpose of the Study:

• To investigate the expression of gag gene-coded proteins in mink cells transformed by the T-8 strain of MCFV.
• To characterize the molecular weight and immunological properties of the expressed viral proteins.
• To compare these findings with precursor polyproteins from other virus-transformed cell lines.

Main Methods:

• Nonproductive transformation of mink cells using the T-8 strain of MCFV.
• Analysis of viral protein expression using molecular weight determination.
• Immunological reactivity testing against known type C virus-coded translational products.

Main Results:

• Mink cells expressed p15 and p12 as a single 90,000-110,000 molecular weight polyprotein.
• This polyprotein lacked detectable immunological reactivity with other known type C viral proteins.
• Similar high-molecular-weight precursor polyproteins were observed in other mammalian sarcoma virus-transformed cell lines.

Conclusions:

• The T-8 strain of MCFV induces a specific gag gene precursor polyprotein in nonproductively transformed mink cells.
• This precursor protein represents a distinct translational product, separate from other known viral proteins.
• Findings support a conserved mechanism of precursor polyprotein formation in cells transformed by related mammalian retroviruses.