Browsing by Author "Deprez, P"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    At least two receptors of asymmetric acetylcholinesterase are present at the synaptic basal lamina of Torpedo electric organ
    (1998) Casanueva, OI; Deprez, P; García-Huidobro, T; Inestrosa, NC
    Asymmetric acetylcholinesterase (AChE) is anchored to the basal lamina (BL) of cholinergic synapses via its collagenic tail, yet the complement of matrix receptors involved in its attachment remains unknown. The development of a novel overlay technique has allowed us to identify two Torpedo BL components that bind asymmetric AChE: a polypeptide of similar to 140kDa and a doublet of 195-215kDa. These were found to stain metachromatically with Coomassie blue R-250, mere solubilized by acetic acid, and were sensitive to collagenase treatment. Upon sequence analysis, the 140kDa polypeptide yielded a characteristic collagenous motif. Another AChE-binding BL constituent, identified by overlay, corresponded to a heparan sulfate proteoglycan. Lastly, we established that this proteoglycan, but not the collagenous proteins, interacted with at least one heparin binding domain of the collagenic tail of AChE. Our results indicate that at least two BL receptors are likely to exist for asymmetric AChE in Torpedo electric organ. (C) 1998 Academic Press.
  • No Thumbnail Available
    Item
    Interaction of the collagen-like tail of asymmetric acetylcholinesterase with heparin depends on triple-helical conformation, sequence and stability
    (2000) Deprez, P; Doss-Pepe, E; Brodsky, B; Inestrosa, NC
    The collagen-like tail of asymmetric acetylcholinesterase (AChE) contains two heparin-binding domains (HBDs) that interact with heparan sulphate proteoglycans, determining the anchoring of the enzyme at the basal lamina and its specific Localization at the neuromuscular junction. Both HBDs are characterized by a cluster of basic residues containing a core with the BBXB consensus sequence (where B represents a basic residue and X a non-basic residue). To study the interaction of such HBDs with heparin we have used synthetic peptides to model the N-terminal and C-terminal sites. CD spectroscopy showed that all peptides are triple-helical at low temperatures, and undergo trimer-to-monomer transitions. Displacement assays of asymmetric AChE bound to heparin were performed using the peptides in both monomeric and triple-helical states. In the monomeric con- formation, all the peptides were able to displace low levels of AChE depending on the basic charge content. In the triplehelical conformation, peptides containing the consensus sequence showed a large increase in the ability to displace bound AChE. Results suggest that the specific binding of the collagen-like-tail peptides to heparin depends both on the presence of the core sequence and on the triple-helical conformation. Moreover, BBXB-containing peptides that are less stable are more effective in displacing AChE, suggesting that the interaction region needs a significant amount of structural flexibility to better accommodate the ligand.