Expression of green or red fluorescent protein (GFP or DsRed) linked proteins in nonmuscle and muscle cells.

The introduction of the green fluorescent protein (GFP) plasmids that allow proteins and peptides to be expressed with a fluorescent tag has had a major impact on the field of cell biology. It has enabled the dynamics of a wide variety of proteins to be analyzed that could not otherwise be detected in live cells. Transient transfections of muscle and nonmuscle cells with plasmids encoding various cytoskeletal proteins ligated to green fluorescent protein or Ds red protein allow changes in the cytoskeletal network to be studied in the same cell for time periods up to several days. With this approach, proteins that could not be purified and directly labeled with fluorescent dyes and microinjected into cells can now be expressed and visualized in a wide variety of cells. Procedures are presented for transfection of the nonmuscle cell, PtK2, and primary cultures of embryonic chick myocytes, and for studying the live transfected cells.