Photolabeling reveals the proximity of the alpha-neurotoxin binding site to the M2 helix of the ion channel in the nicotinic acetylcholine receptor.
AUTOR(ES)
Machold, J
RESUMO
A photoactivatable derivative of neurotoxin II from Naja naja oxiana containing a 125I-labeled p-azidosalicylamidoethyl-1,3'-dithiopropyl label at Lys-25 forms a photo-induced cross-link with the delta subunit of the membrane-bound Torpedo californica nicotinic acetylcholine receptor (AChR). The cross-linked radioactive receptor peptide was isolated by reverse-phase HPLC after tryptic digestion of the labeled delta subunit. The sequence of this peptide, delta-(260-277), and the position of the label at Ala-268 were established by matrix-assisted laser-desorption-ionization mass spectrometry based on the molecular mass and on post-source decay fragment analysis. With the known dimensions of the AChR molecule, of the photolabel, and of alpha-neurotoxin, finding the cross-link at delta Ala-268 (located in the upper part of the channel-forming transmembrane helix M2) means that the center of the alpha-neurotoxin binding site is situated at least approximately 40 A from the extracellular surface of the AChR, proximal to the channel axis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=41323Documentos Relacionados
- Energy and Structure of the M2 Helix in Acetylcholine Receptor-Channel Gating
- Triphenylmethylphosphonium is an ion channel ligand of the nicotinic acetylcholine receptor.
- Mutations at two distinct sites within the channel domain M2 alter calcium permeability of neuronal alpha 7 nicotinic receptor.
- M2 delta, a candidate for the structure lining the ionic channel of the nicotinic cholinergic receptor.
- Conformation of acetylcholine bound to the nicotinic acetylcholine receptor.