TY - JOUR
T1 - Asymmetric contribution of the conserved disulfide loop to subunit oligomerization and assembly of the nicotinic acetylcholine receptor
AU - Fu, Da Xiong
AU - Sine, Steven M.
PY - 1996
Y1 - 1996
N2 - The acetylcholine receptor (AChR) at the motor synapse is a pentamer of homologous subunits with the composition α2βγδ. Owing to the circular arrangement of subunits that forms a central ion channel, each subunit interface contains contributions from opposite faces of each subunit, designated + and -. Common to all subunits of the AChR and members of its superfamily is a disulfide loop formed between cysteines 128 and 142 of the major extracellular domain. To gain insight into the structural contribution of the disulfide loop and its possible location, we mutated the invariant proline at position 136 to glycine (P136G) and examined subunit assembly. When introduced into any AChR subunit, P136G disrupted assembly by affecting the - face of the subunit, suggesting equivalent positioning of the loop in each subunit and localization to the - face. Also, the contribution of the loop in the overall assembly process differed for each subunit. In the β and γ subunits, P136G prevented assembly of higher order heteroligomers, whereas in the α and δ subunits, P136G prevented transport of assembled pentamers to the cell surface. The results demonstrate asymmetry in the contribution of the disulfide loop to formation of subunit interfaces, and that the loop in each subunit contributes at different stages of assembly.
AB - The acetylcholine receptor (AChR) at the motor synapse is a pentamer of homologous subunits with the composition α2βγδ. Owing to the circular arrangement of subunits that forms a central ion channel, each subunit interface contains contributions from opposite faces of each subunit, designated + and -. Common to all subunits of the AChR and members of its superfamily is a disulfide loop formed between cysteines 128 and 142 of the major extracellular domain. To gain insight into the structural contribution of the disulfide loop and its possible location, we mutated the invariant proline at position 136 to glycine (P136G) and examined subunit assembly. When introduced into any AChR subunit, P136G disrupted assembly by affecting the - face of the subunit, suggesting equivalent positioning of the loop in each subunit and localization to the - face. Also, the contribution of the loop in the overall assembly process differed for each subunit. In the β and γ subunits, P136G prevented assembly of higher order heteroligomers, whereas in the α and δ subunits, P136G prevented transport of assembled pentamers to the cell surface. The results demonstrate asymmetry in the contribution of the disulfide loop to formation of subunit interfaces, and that the loop in each subunit contributes at different stages of assembly.
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U2 - 10.1074/jbc.271.49.31479
DO - 10.1074/jbc.271.49.31479
M3 - Article
C2 - 8940161
AN - SCOPUS:0029969731
SN - 0021-9258
VL - 271
SP - 31479
EP - 31484
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 49
ER -