The amino acid residues 1-128 in the alpha subunit of the nicotinic acetylcholine receptor contain assembly signals.
Expression of nicotinic acetylcholine receptor (AChR) involves complex processes including assembly of different receptor subunits into hetero-oligomers. To identify the minimal N-terminal region involved in AChR subunit association, we used a dominant negative assay. Co-expression of fragments of the alpha subunit, containing the N-terminal extracellular domain and transmembrane domain 1 (TM 1), with the parental AChR subunits in Xenopus oocytes blocked functional expression of the receptor. In contrast, co-expression of N-terminal extracellular fragments without TM1 failed to inhibit functional expression of AChRs, but altered the functional properties of co-expressed parental AChRs. Furthermore, when these alpha subunit fragments were co-expressed with the beta, gamma, and delta subunits, they were co-immunoprecipitated with a mixture of beta, gamma, and delta subunit specific antibodies. These results suggest that 'assembly signals' are confined to a local structure in the N-terminal extracellular domain. Our findings also indicate that an assembly step may be a target for genetic intervention not only to block the expression of functional receptors, but also to alter the function of the receptor.
Sumikawa
K
K
Department of Psychobiology, University of California, Irvine 92717-4550.
Nishizaki
T
T
D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D001483:Base Sequence; D005260:Female; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry*; D021382:Protein Sorting Signals / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011978:Receptors, Nicotinic / Q000737:chemistry*; D014101:Torpedo; D014981:Xenopus
D000596:Amino Acids; D010446:Peptide Fragments; D021382:Protein Sorting Signals; D011978:Receptors, Nicotinic