Assembly and regulation of acetylcholinesterase at the vertebrate neuromuscular junction. 2008

R L Rotundo, and C A Ruiz, and E Marrero, and L M Kimbell, and S G Rossi, and T Rosenberry, and A Darr, and P Tsoulfas
Department of Cell Biology and Anatomy, The University of Miami School of Medicine, 1600 N.W. 10th Avenue, Miami, FL 33136, USA. rrotundo@miami.edu

The collagen-tailed form of acetylcholinesterase (ColQ-AChE) is the major if not unique form of the enzyme associated with the neuromuscular junction (NMJ). This enzyme form consists of catalytic and non-catalytic subunits encoded by separate genes, assembled as three enzymatic tetramers attached to the three-stranded collagen-like tail (ColQ). This synaptic form of the enzyme is tightly attached to the basal lamina associated with the glycosaminoglycan perlecan. Fasciculin-2 is a snake toxin that binds tightly to AChE. Localization of junctional AChE on frozen sections of muscle with fluorescent Fasciculin-2 shows that the labeled toxin dissociates with a half-life of about 36 h. The fluorescent toxin can subsequently be taken up by the muscle fibers by endocytosis giving the appearance of enzyme recycling. Newly synthesized AChE molecules undergo a lengthy series of processing events before final transport to the cell surface and association with the synaptic basal lamina. Following co-translational glycosylation the catalytic subunit polypeptide chain interacts with several molecular chaperones, glycosidases and glycosyltransferases to produce a catalytically active enzyme that can subsequently bind to one of two non-catalytic subunits. These molecular chaperones can be rate limiting steps in the assembly process. Treatment of muscle cells with a synthetic peptide containing the PRAD attachment sequence and a KDEL retention signal results in a large increase in assembled and exportable AChE, providing an additional level of post-translational control. Finally, we have found that Pumilio2, a member of the PUF family of RNA-binding proteins, is highly concentrated at the vertebrate neuromuscular junction where it plays an important role in regulating AChE translation through binding to a highly conserved NANOS response element in the 3'-UTR. Together, these studies define several new levels of AChE regulation in electrically excitable cells.

UI MeSH Term Description Entries
D009469 Neuromuscular Junction The synapse between a neuron and a muscle. Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D004546 Elapid Venoms Venoms from snakes of the family Elapidae, including cobras, kraits, mambas, coral, tiger, and Australian snakes. The venoms contain polypeptide toxins of various kinds, cytolytic, hemolytic, and neurotoxic factors, but fewer enzymes than viper or crotalid venoms. Many of the toxins have been characterized. Cobra Venoms,Elapidae Venom,Elapidae Venoms,Naja Venoms,Cobra Venom,Elapid Venom,Hydrophid Venom,Hydrophid Venoms,King Cobra Venom,Naja Venom,Ophiophagus hannah Venom,Sea Snake Venom,Sea Snake Venoms,Venom, Cobra,Venom, Elapid,Venom, Elapidae,Venom, Hydrophid,Venom, King Cobra,Venom, Naja,Venom, Ophiophagus hannah,Venom, Sea Snake,Venoms, Cobra,Venoms, Elapid,Venoms, Elapidae,Venoms, Hydrophid,Venoms, Naja,Venoms, Sea Snake
D000110 Acetylcholinesterase An enzyme that catalyzes the hydrolysis of ACETYLCHOLINE to CHOLINE and acetate. In the CNS, this enzyme plays a role in the function of peripheral neuromuscular junctions. EC 3.1.1.7. Acetylcholine Hydrolase,Acetylthiocholinesterase,Hydrolase, Acetylcholine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014157 Transcription Factors Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process. Transcription Factor,Factor, Transcription,Factors, Transcription
D014176 Protein Biosynthesis The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS. Genetic Translation,Peptide Biosynthesis, Ribosomal,Protein Translation,Translation, Genetic,Protein Biosynthesis, Ribosomal,Protein Synthesis, Ribosomal,Ribosomal Peptide Biosynthesis,mRNA Translation,Biosynthesis, Protein,Biosynthesis, Ribosomal Peptide,Biosynthesis, Ribosomal Protein,Genetic Translations,Ribosomal Protein Biosynthesis,Ribosomal Protein Synthesis,Synthesis, Ribosomal Protein,Translation, Protein,Translation, mRNA,mRNA Translations
D014714 Vertebrates Animals having a vertebral column, members of the phylum Chordata, subphylum Craniata comprising mammals, birds, reptiles, amphibians, and fishes. Vertebrate
D016601 RNA-Binding Proteins Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA. Double-Stranded RNA-Binding Protein,Double-Stranded RNA-Binding Proteins,ds RNA-Binding Protein,RNA-Binding Protein,ds RNA-Binding Proteins,Double Stranded RNA Binding Protein,Double Stranded RNA Binding Proteins,Protein, Double-Stranded RNA-Binding,Protein, ds RNA-Binding,RNA Binding Protein,RNA Binding Proteins,RNA-Binding Protein, Double-Stranded,RNA-Binding Protein, ds,RNA-Binding Proteins, Double-Stranded,ds RNA Binding Protein
D018832 Molecular Chaperones A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures. Chaperones, Molecular,Chaperone, Molecular,Molecular Chaperone

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