Serum spreading factor (vitronectin) is present at the cell surface and in tissues

Area of Science:

• Biochemistry
• Cell Biology
• Immunology

Background:

• A cell attachment-promoting protein was partially purified from human serum.
• Monoclonal antibodies were generated against this protein, also known as serum spreading factor.

Purpose of the Study:

• To characterize the protein using the developed monoclonal antibodies.
• To investigate the protein's distribution and function in human tissues and cells.

Main Methods:

• Monoclonal antibody production and selection.
• Immunochromatography and affinity chromatography (heparin-Sepharose).
• Sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE).
• Immunofluorescent staining of tissues and cultured cells.

Main Results:

• Two polypeptides of 65 and 75 kilodaltons were isolated, possessing cell attachment activity.
• These polypeptides bound to the monoclonal antibodies and were found in loose connective tissue and on fibroblast extracellular matrix.
• The protein exhibited a fibrillar pattern in tissues, overlapping with fibronectin.

Conclusions:

• The protein, proposed to be named "vitronectin," exhibits adhesive properties and binds to glass.
• Vitronectin is present in human plasma, tissues, and on cultured fibroblasts, playing a role in cell attachment and connective tissue structure.