What is the Function of a Protein?
- Molecular/biochemical function: e.g. phosphatase, DNA-binding protein.
- Cellular function: e.g. growth factor signaling pathway, amino acid metabolism, DNA synthesis.
- Biological funciton: e.g. control of bone growth, regulation of flower development.
Another complication is that in bacteria and unicellular eukaryotes, the cellular and biological functions of a protein would be combined, whereas in multicellular organisms they could be separated. As an example, the info below shows the possible classifications for the human protein glucokinase.
- Molecular/biochemical function: kinase, substrate glucose
- Cellular functions: glycolysis, glucose metabolism
- Biological function: expressed specifically in pancreatic Beta-cells and hepatocytes, primary regulator of glucose-controlled insulin secretion, loss of function mutations cause diabetes, gain of function mutations can cause hyperinsulinism.