title: Photoaffinity labeling of the nucleotide binding site of actin.
abstract: Rabbit skeletal muscle actin was photoaffinity-labeled by the nucleotide analogue 8-azidoadenosine 5'-triphosphate. In both G-actin and F-actin about 25% covalent incorporation was achieved. The labeled actins were digested with cyanogen bromide, and the labeled peptides were isolated and sequenced. In F-actin the label was bound primarily to Lys-336, while in G-actin the label was bound to Lys-336 or to Trp-356. The results indicate that the nucleotide binding site is near the phalloidin binding site of actin [Vanderkerckhove, J., Deboben, A., Nassal, M., & Wieland, T. (1985) EMBO J. 4, 2815-2818]. The binding of the azido group to Trp-356 in G-actin but not in F-actin may indicate that a change in the conformation of actin occurs in this region.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism*; D000595:Amino Acid Sequence; D001386:Azides / Q000138:chemical synthesis / Q000378:metabolism*; D002250:Carbon Radioisotopes; D007700:Kinetics; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D000199:Actins; D000345:Affinity Labels; D001386:Azides; D002250:Carbon Radioisotopes; D010446:Peptide Fragments; C017040:8-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate