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Monkey Kidney Cells with mEmerald-Lysosomes and mApple-α-Actinin

The growth inhibitory activity in conditioned medium of African green monkey kidney epithelial cells (BS-C-1 line) has been shown to arise from transforming growth factor β2 (TGF-β2). The purified growth inhibitor from BSC-1 cells and the TGF-β1 from human platelets has proved to have almost identical biological activity and to compete for binding to the same cell membrane receptor. These conclusions suggest that the growth inhibitor and the TGF-β are similar molecules. The data also shows that depending on the experimental conditions, the same purified polypeptide can either stimulate or inhibit cell proliferation. In the digital video sequence in this section, BS-C-1 cells can be seen expressing mEmerald fused to lysosomes and mApple fused to alpha-actinin, which is an actin-binding protein.

The fluorescent protein fused to alpha-actinin, mApple, is a red fluorescent protein that matures rapidly and is bright and photostable. The fluorescent protein was developed from the results of a team led by Roger Tsien that successfully identified red fluorescent protein variants with improved photostability through a novel screening process. The excitation and emission peaks of mApple occur at 568 and 592 nanometers, respectively. The green fluorescent protein, mEmerald, employed to visualize lysosomes in the digital video sequences, exhibits peak excitation at 487 nanometers and peak emission at 509 nanometers.