Cell surface coat of hamster fibroblasts

Area of Science:

• Cell Biology
• Biochemistry
• Oncology

Background:

• The unique high-speed centrifugation (UHF) fraction from NIL 8 hamster embryo fibroblasts is known to contain the LETS protein and other significant proteins.
• This fraction also displays notable enzymatic activities, including 5'-nucleotidase, alkaline phosphatase, and galactosyl transferase.
• Ruthenium red staining indicates the presence of cell coat components within this UHF fraction.

Purpose of the Study:

• To characterize the protein and enzymatic composition of the UHF fraction from normal and virus-transformed hamster cells.
• To investigate alterations in protein profiles and enzymatic activities associated with viral transformation.
• To compare the cell coat composition between normal and transformed fibroblasts.

Main Methods:

• Isolation and fractionation of cellular components from NIL 8 hamster embryo fibroblasts and hamster sarcoma virus-transformed cells using unique high-speed centrifugation (UHF).
• Analysis of protein composition within the UHF fraction using gel electrophoresis.
• Assay of enzymatic activities, specifically 5'-nucleotidase, alkaline phosphatase, and galactosyl transferase.
• Staining with ruthenium red to identify cell coat components.

Main Results:

• The UHF fraction from NIL 8 cells contains the LETS protein, 5'-nucleotidase, alkaline phosphatase, and galactosyl transferase.
• Alkaline phosphatase and galactosyl transferase in the UHF fraction appear distinct from membrane-bound counterparts.
• The UHF fraction from transformed cells shows a similar protein profile but lacks LETS protein and at least two other major proteins.
• Transformed cells exhibit altered alkaline phosphatase distribution and significantly reduced galactosyl transferase levels in the UHF fraction.

Conclusions:

• Viral transformation significantly alters the protein composition and enzymatic activity of the UHF fraction in hamster fibroblasts.
• The LETS protein and specific enzymatic activities (alkaline phosphatase, galactosyl transferase) are affected by viral transformation, suggesting a role in cell coat changes.
• These findings highlight biochemical differences in the cell surface components between normal and oncogenically transformed cells.