Localization of a Heterotrimeric G Protein γ Subunit to Focal Adhesions and Associated Stress Fibers

• Published in: The Journal of cell biology Vol. 126; no. 3; pp. 811 - 819
• Main Authors: Hansen, Carl A., Schroering, Allen G., Carey, David J., Robishaw, Janet D.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.08.1994; The Rockefeller University Press
• Subjects: Actins; Animals; Antibodies; Biological and medical sciences; Blotting, Western; Cell Adhesion - physiology; Cell Division - physiology; Cell Membrane - chemistry; Cell physiology; Cells; Cells, Cultured; Extracellular Matrix - physiology; Fibroblasts; Focal adhesions; Fundamental and applied biological sciences. Psychology; GTP-Binding Proteins - analysis; GTP-Binding Proteins - physiology; Microscopy, Fluorescence; Molecular and cellular biology; Physiological regulation; Rats; Rats, Sprague-Dawley; Receptors; Saponins; Schwann cells; Signal Transduction; Space life sciences; Stress fibers; Vinculin - analysis; Cell proliferation; Vertebrata; Mammalia; Rat; Rodentia; Cell cell interaction; Extracellular matrix; Localization; Adhesion; G protein
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.126.3.811

Signal transducing heterotrimeric G proteins are responsible for coupling a large number of cell surface receptors to the appropriate effector(s). Of the three subunits, 16 α, 4 β, and 5 γ subunits have been characterized, indicating a potential for over 300 unique combinations of heterotrimeric G proteins. To begin deciphering the unique G protein combinations that couple specific receptors with effectors, we examined the subcellular localization of the γ subunits. Using anti-peptide antibodies specific for each of the known γ subunits, neonatal cardiac fibroblasts were screened by standard immunocytochemistry. The anti-γ 5 subunit antibody yielded a highly distinctive pattern of intensely fluorescent regions near the periphery of the cell that tended to protrude into the cell in a fibrous pattern. Dual staining with anti-vinculin antibody showed co-localization of the γ 5 subunit with vinculin. In addition, the γ 5 subunit staining extended a short distance out from the vinculin pattern along the protruding stress fiber, as revealed by double staining with phalloidin. These data indicated that the γ 5 subunit was localized to areas of focal adhesion. Dual staining of rat aortic smooth muscle cells and Schwann cells also indicated co-localization of the γ 5 subunit and vinculin, suggesting that the association of the γ 5 subunit with areas of focal adhesion was wide-spread.