Acetylcholinesterase associates differently with its anchoring proteins ColQ and PRiMA.
Acetylcholinesterase tetramers are inserted in the basal lamina of neuromuscular junctions or anchored in cell membranes through the interaction of four C-terminal t peptides with proline-rich attachment domains (PRADs) of cholinesterase-associated collagen Q (ColQ) or of the transmembrane protein PRiMA (proline-rich membrane anchor). ColQ and PRiMA differ in the length of their proline-rich motifs (10 and 15 residues, respectively). ColQ has two cysteines upstream of the PRAD, which are disulfide-linked to two AChE(T) subunits ("heavy" dimer), and the other two subunits are disulfide-linked together ("light" dimer). In contrast, PRiMA has four cysteines upstream of the PRAD. We examined whether these cysteines could be linked to AChE(T) subunits in complexes formed with PRiMA in transfected COS cells and in the mammalian brain. For comparison, we studied complexes formed with N-terminal fragments of ColQ, N-terminal fragments of PRiMA, and chimeras in which the upstream regions containing the cysteines were exchanged. We also compared the effect of mutations in the t peptides on their association with the two PRADs. We report that the two PRADs differ in their interaction with AChE(T) subunits; in complexes formed with the PRAD of PRiMA, we observed light dimers, but very few heavy dimers, even though such dimers were formed with the PQ chimera in which the N-terminal region of PRiMA was associated with the PRAD of ColQ. Complexes with PQ or with PRiMA contained heavy components, which migrated abnormally in SDS-PAGE but probably resulted from disulfide bonding of four AChE(T) subunits with the four upstream cysteines of the associated protein.
Noureddine
Hiba
H
Laboratoire de Neurobiologie, Centre National de la Recherche Scientifique, UMR 8544, Ecole Normale Supérieure, 46 Rue d'Ulm, Paris, France.
Carvalho
Stéphanie
S
Schmitt
Claudine
C
Massoulié
Jean
J
Bon
Suzanne
S
D000110:Acetylcholinesterase / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003094:Collagen / Q000737:chemistry / Q000502:physiology*; D003545:Cysteine / Q000737:chemistry; D019281:Dimerization; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C486718:prima1 protein, mouse; D003094:Collagen; D000110:Acetylcholinesterase; D003545:Cysteine