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Human serum spreading factor: relationship to somatomedin B
The Journal of Clinical Endocrinology and Metabolism
|November 1, 1984
Summary
Human serum spreading factor (SF) is a glycoprotein that aids cell attachment and spreading. It does not exhibit growth factor activity, suggesting it functions as a substratum molecule.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Serum spreading factor (SF) is a human blood glycoprotein.
- SF promotes cell attachment, spreading, migration, proliferation, and differentiation.
- SF shares sequence identity with somatomedin B (SmB).
Purpose of the Study:
- To determine the NH2-terminal amino acid sequence of SF.
- To investigate the relationship between SF and somatomedin B (SmB).
- To assess the biological activity of SF in cell culture and its response to GH levels.
Main Methods:
- NH2-terminal amino acid sequencing of SF.
- Immunoassay of SF in human plasma.
- Cell growth assays to detect mitogenic activity.
Main Results:
- The NH2-terminal sequence of SF matched that of SmB.
- Serum SF levels showed no significant GH responsiveness.
- Purified SF lacked mitogenic activity in cell growth assays.
Conclusions:
- SF functions as a substratum molecule, not a peptide growth factor.
- The mitogenic activity in SmB preparations is likely due to a contaminant, not SmB itself.
- SF's biological effects are mediated through its role as a cell culture substratum.