Fig. 1: Oocytes expressing a CFP-labeled G protein activated K+ channels, GIRK. The channel is composed of Cerulean Fluorescent Protein (YFP)-fused GIRK1 subunit, coexpressed with a wild-type GIRK2 subunit. The image was taken using the ×5 objective, focused on the midline (equator) of the oocytes.
Fig. 2: Oocytes expressing a Yellow Fluorescent Protein (YFP)-fused G protein α subunit, Gαi3. The image was taken using the ×5 objective, focused on the midline (equator) of the oocytes.
Fig. 3. Zoom on one of the oocytes shown in Fig. 2, using the ×20 objective and an optical zoom of ×2. The focus was approximately at the equator of the oocyte, the thus the optical slice is a transverse plane through about the middle of the oocyte. Only the plasma membrane and a thin submembrane region are labeled with the expressed protein (which normally accumulates in the plasma membrane anyway), the rest of the oocyte being non-transparent.
Fig. 4. Zoom on one of the oocytes shown in Fig. 2, using the ×20 objective and an optical zoom of ×2. In this case, the focus was on the bottom surface of the oocytes, so that the optical slice shows a transverse plane through this part of the cell, as if viewing the oocyte's membrane and the adjacent submembrane region (about 5 μm thick) from below or above. The optically dense circles are the pigment granules, each about 1 μm in diameter.Methods: Oocytes were devitellinized and injected with the RNAs encoding the different proteins 3-5 before the imaging experiment. All images were taken with the Zeiss 510 Meta confocal microscope, working in its spectral mode. Standard virtual coloring was used in all images. The spectra were collected with 405 nm (CFP excitation; emission was collected between 450 and 610 nm) and 514 nm (YFP excitation; emission was collected between 524 and 610 nm) laser lines.
