GTP-binding proteins in brain and neutrophil are tethered to the plasma membrane via their amino termini.
Using specific antisera raised against synthetic peptides, we find that three distinct GTP-binding protein alpha subunits remain bound to the plasma membrane even after activation with nonhydrolyzable GTP analog. Trypsin cleaves each alpha subunit at a site near the amino-terminus, and quantitatively releases the large fragment (comprising all but an amino-terminal 2 kDa piece) from the membrane. Our results indicate that alpha subunits are essentially cytoplasmic proteins tethered to the inner surface of the membrane via an amino terminal stalk.
D000818:Animals; D001921:Brain / Q000648:ultrastructure; D002417:Cattle; D000939:Epitopes; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D008565:Membrane Proteins / Q000378:metabolism*; D009504:Neutrophils / Q000648:ultrastructure; D010446:Peptide Fragments / Q000276:immunology; D011485:Protein Binding; D011487:Protein Conformation; D012995:Solubility; D014357:Trypsin
D000939:Epitopes; D008565:Membrane Proteins; D010446:Peptide Fragments; D014357:Trypsin; D019204:GTP-Binding Proteins