Modified fluorescent protein

A method of detecting a pressure or a change in pressure applied to a liquid containing:

• A. a modified fluorescent protein (MFP),
• (1) wherein the MFP comprises a wild type green fluorescent protein of 238 amino acids isolated from jellyfish (WFP) modified with at least one amino acid inserted into a position corresponding to a position between 144 th and 145 th amino acids;
• or
• (2) wherein the MFP is a fluorescent protein derived from the WFP of A(1) that is further modified to be yellow fluorescent protein (YFP), cyan fluorescent protein (CFP), enhanced green fluorescent protein (EGFP), enhanced yellow fluorescent protein (EYFP), or enhanced cyan fluorescent protein (ECFP);
• or
• B. a fusion fluorescent protein (FFP), wherein the FFP is a fusion fluorescent protein in which the MFP is fused with a fluorescent protein having an excitation spectrum different from an excitation spectrum of the MFP,
• the method comprising:
• detecting fluorescent intentsity of the MFP or FFP;
• and
• comparing the detected fluorescent intensity to (a) the fluorescent intensity of a control wild-type fluorescent protein or (b) the fluorescent intensity of the MFP or FFP when no pressure is applied, to determine the pressure or the change in pressure applied to the liquid containing the MFP or FFP,
• wherein when pressure applied to the liquid containing the MFP or FFP increases, the fluorescent intensity of the MFP or FFP increases, and when pressure applied to the liquid containing the MFP or FFP decreases, the fluorescent intensity of the MFP or FFP decreases.