Method for evaluating receptor-type tyrosine kinase activity

A method for evaluating an activity of a receptor tyrosine kinase (RTK), the method comprising:

• i) a step (A1) for determining diffusion dynamics A1 of the RTK by contacting a target substance with a cell that expresses a labeled receptor tyrosine kinase (RTK) on a cell membrane;
• a step (B1) for determining diffusion dynamics B1 of the RTK by contacting the target substance and a ligand that activates the RTK with a cell that expresses the labeled receptor tyrosine kinase (RTK) on a cell membrane;
• a step (C1) for calculating a ratio of the diffusion dynamics A1 of the RTK obtained at the step (A1) and the diffusion dynamics B1 of the RTK obtained at the step (B1) (diffusion dynamics B1/diffusion dynamics A1);
• and
• a step (D1) for evaluating an effect of the target substance on the RTK activity by comparing the ratio of the diffusion dynamics (diffusion dynamics B1/diffusion dynamics A1) obtained at the step (C1) with a threshold, wherein
• at the step (D1), the ratio of the diffusion dynamics (diffusion dynamics B1/diffusion dynamics A1) obtained at the step (C1) being equal to or greater than the threshold can indicate that the target substance has an effect on a molecular function of the RTK;
• or
• ii) a step (A2) for determining diffusion dynamics A2 of the RTK without contacting a target substance with a cell that expresses a labeled receptor tyrosine kinase (RTK) on a cell membrane;
• a step (B2) for determining diffusion dynamics B2 of the RTK by contacting the target substance with the cell that expresses the labeled receptor tyrosine kinase (RTK) on a cell membrane;
• a step (C2) for calculating a ratio of the diffusion dynamics A2 of the RTK obtained at the step (A2) and the diffusion dynamics B2 of the RTK obtained at the step (B2) (diffusion dynamics B2/diffusion dynamics A2), or a difference between the diffusion dynamics B2 and the diffusion dynamics A2 (diffusion dynamics B2−diffusion dynamics A2);
• a step (E2) for determining diffusion dynamics E2 of the RTK without contacting the target substance with the cell that expresses the labeled receptor tyrosine kinase (RTK) on a cell membrane;
• a step (F2) for determining diffusion dynamics F2 of the RTK by contacting a solution not containing the target substance with the cell at the step (E2);
• a step (G2) for calculating a ratio of the diffusion dynamics E2 of the RTK obtained at the step (E2) and the diffusion dynamics F2 of the RTK obtained at the step (F2) (diffusion dynamics F2/diffusion dynamics E2), or a difference between the diffusion dynamics E2 and the diffusion dynamics F2 (diffusion dynamics F2−diffusion dynamics E2);
• and
• a step (D2) for evaluating the RTK activity of the target substance by comparing an absolute value of a difference between the ratios of the diffusion dynamics obtained at the step (C2) (diffusion dynamics B2/diffusion dynamics A2) and the ratio of the diffusion dynamics obtained at the step (G2) (diffusion dynamics F2/diffusion dynamics E2) ([diffusion dynamics B2/diffusion dynamics A2]−[diffusion dynamics F2/diffusion dynamics E2]), or an absolute value of a difference between the difference of the diffusion dynamics obtained at the step (C2) (diffusion dynamics B2−diffusion dynamics A2) and the difference of the diffusion dynamics obtained at the step (G2) (diffusion dynamics F2−diffusion dynamics E2) ([diffusion dynamics B2−diffusion dynamics A2]−[diffusion dynamics F2−diffusion dynamics E2]), with a threshold,
• wherein
• at the step (D2), the absolute value of the difference between the ratios of the diffusion dynamics or the absolute value of the difference in the diffusion dynamics obtained at the step (G2) being equal to or greater than the threshold can indicate that the target substance has an effect on the RTK's molecular function not limited to a phosphorylation activity.