title: Immunolocalization of G(alpha)i-3 in foetal lung fibroblasts.
abstract: Guanosine triphosphate (GTP)-binding proteins or G proteins are involved in a wide variety of well-recognized signalling activities between cell surface receptors and effectors. The heterotrimeric G proteins have alpha,beta and gamma subunits organized in a trimeric structure. The aim of this study was to localize G(alpha)i-3, an important heterotrimeric G protein, in foetal lung cells. Using a foetal lung fibroblast cell line (RFL-6), the localization of G(alpha)i-3 was determined by immunofluorescence using a specific antibody to G(alpha)i-3, colocalization with a lectin known to bind the Golgi complex and Western blotting of RFL-6 cellular membrane proteins. This study identified G(alpha)i-3 on the Golgi membranes in rat foetal lung cells. Treatment with cycloheximide, to block protein synthesis, diminished the cytosolic distribution of the protein, but intense Golgi staining remained. G(alpha)i-3, therefore, appears to be part of the Golgi complex and not present transiently during protein synthesis. In the nonpolar foetal lung fibroblasts studied, the intracellular concentration of G(alpha)i-3 suggests a role for this protein in the intracellular trafficking and regulation of proteins needed for normal lung development.
authors.affiliation: Stanford University School of Medicine, California, USA.
authors.forename: A
authors.initials: A
authors.lastname: Dosanjh
mesh_terms: D000818:Animals; D000906:Antibodies; D015153:Blotting, Western; D002460:Cell Line; D005333:Fetus; D005347:Fibroblasts / Q000737:chemistry* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000032:analysis* / Q000276:immunology; D006056:Golgi Apparatus / Q000737:chemistry; D008168:Lung / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000906:Antibodies; D019204:GTP-Binding Proteins