Function and structure of +-MITF, mi-MITF, and ew-MITF.

(A) The effect of coexpression of +-MITF, mi-MITF, orew-MITF on the luciferase activity under the control of the Gr B promoter. Various reporter and effector constructs were introduced into P815 cells by electroporation. The value of the luciferase activity was divided by the value obtained with the transfection of pGr B-42 alone and was shown as the relative luciferase activity. The bars represent the mean ± SE of 3 independent experiments. In some cases, the SE was too small to be shown by the bars. *P < .01 by t test when compared with the control, in which expression vector containing no insert was cotransfected. (B) Comparison of amino acid sequence among +-MITF, mi-MITF, and ew-MITF. The amino acids are numbered from the initiation codon. Bars in mi-MITF orew-MITF show the deleted amino acids. One of 3 arginines (amino acid 215-217) is deleted in mi-MITF. It is unclear which one has been deleted. Twenty-one amino acids that compose the basic domain are boxed.