The cytosolic N-terminal region of heterologously-expressed transmembrane channel-like protein 1 (TMC1) can be cleaved in HEK293 cells
Fig 1
The N-terminal (Nt) region of heterologously-expressed mTMC1 accumulated in nuclei of a small population of HEK293 cells.
(A) Amino acid sequences of the N-terminal (Nt) regions of mouse TMC1 (mTMC1) and human TMC1 (hTMC1). cNLSs: classical nuclear localization signals. TM1: first transmembrane region. (B) A membrane topology of mTMC1 and the position of the antigen (from 57th aspartate to 75th glycine, D57-G75) of the mTMC1 antibody are shown. Appearance of the Nt region of mTMC1 in a nucleus implies its cleavage and transport into the nucleus. (C) Images of confocal microscopy. Upper two figures are images of mTMC1 transfected cells and lower two figures are images of mock transfected cells. The left figure is a merged image of a green-channel image and a bright-field image, and a blue-channel image was also merged in the right figure. Green signals show the staining of the Nt region of mTMC1, and blue signals show nuclear staining of DAPI. A red arrow indicates a cell where the Nt region of mTMC1 accumulated in the nucleus. White arrows indicate cells where the Nt region of mTMC1 was localized in the cytoplasm (i.e. a normal distribution of heterologously-expressed TMC1). White scale bars indicate 10 μm. (D) A histogram of percentage of cell number, which shows how many cells highly/poorly accumulate the Nt region of mTMC1 in their nuclei. The horizontal axis shows percentage of the signal intensity (green fluorescence of Alexa Fluor 488 i.e. the staining of the Nt region of mTMC1) in the nucleus to that in the whole cell area of each cell. Each class interval of the signal percentage is 10%. Shown are mean ± s.e.m. (n = 4).