High Affinity Binding of α-Latrotoxin to Recombinant Neurexin Iα

Davletov, Bazbek; Krasnoperov, Valery; Hata, Yoshinobu; Petrenko, Alexander G.; Südhof, Thomas C.

doi:10.1074/jbc.270.41.23903

Cited by 59 publications

(75 citation statements)

References 23 publications

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“…A second reported ligand for latrophilin-1 is the presynaptic transmembrane protein neurexin (Boucard et al, 2012). Of interest, neurexin, like latrophilin-1, is a cellular target of latrotoxin (Davletov et al, 1995). Like teneurin-2, neurexin was shown to interact with latrophilin-1 with nanomolar affinity to form heterophilic complexes at cell-cell junctions (Boucard et al, 2012).…”

Section: Importance Of the N Terminus For Adhesion Gpcr Signalingmentioning

confidence: 99%

Adhesion G Protein-Coupled Receptors: Signaling, Pharmacology, and Mechanisms of Activation

2012

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The adhesion G protein-coupled receptors (GPCRs) are a distinct family of more than 30 receptors in vertebrate genomes. These receptors have been shown to play pivotal roles in a diverse range of biological functions and are characterized by extremely large N termini featuring various adhesion domains capable of mediating cell-cell and cell-matrix interactions. The adhesion GPCR N termini also contain GPCR proteolytic site motifs that undergo autocatalytic cleavage during receptor processing to create mature GPCRs existing as noncovalently attached complexes between the N terminus and transmembrane regions. There is mounting evidence that adhesion GPCRs can couple to G proteins to activate a variety of different downstream signaling pathways. Furthermore, recent studies have demonstrated that adhesion GPCR N termini can bind to multiple ligands, which may differentially activate receptor signaling and/or mediate cell adhesion. In addition, studies on several distinct adhesion GPCRs have revealed that truncations of the N termini result in constitutively active receptors, suggesting a model of receptor activation in which removal of the N terminus may be a key event in stimulating receptor signaling. Because mutations to certain adhesion GPCRs cause human disease and because many members of this receptor family exhibit highly discrete distribution patterns in different tissues, the adhesion GPCRs represent a class of potentially important drug targets that have not yet been exploited. For this reason, understanding the mechanisms of activation for these receptors and elucidating their downstream signaling pathways can provide insights with the potential to lead to novel therapeutic agents.

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Section: Importance Of the N Terminus For Adhesion Gpcr Signalingmentioning

confidence: 99%

Adhesion G Protein-Coupled Receptors: Signaling, Pharmacology, and Mechanisms of Activation

2012

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“…Neurexin I␣ and CL1 bind ␣-latrotoxin with similarly high affinities but exhibit strikingly different properties. Neurexin I␣ binds ␣-latrotoxin only in the presence of Ca 2ϩ , suggesting that ␣-latrotoxin does not mediate the Ca 2ϩ -independent effect of ␣-latrotoxin (18). CL1, in contrast, binds ␣-latrotoxin Ca 2ϩ independently.…”

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confidence: 97%

α-Latrotoxin Receptor CIRL/Latrophilin 1 (CL1) Defines an Unusual Family of Ubiquitous G-protein-linked Receptors

Sugita

Ichtchenko

Khvotchev

et al. 1998

Journal of Biological Chemistry

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164

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␣-Latrotoxin, a potent excitatory neurotoxin, binds to two receptors: a G-protein-coupled receptor called CIRL/latrophilin 1 (CL1) and a cell-surface protein called neurexin I␣. We now show that CL1 belongs to a family of closely related receptors called CL1, CL2, and CL3. CLs exhibit an unusual multidomain structure with similar alternative splicing and large extra-and intracellular sequences. CLs share domains with other G-protein-coupled receptors, lectins, and olfactomedins/ myocilin. In addition, CLs contain a novel, widespread cysteine-rich domain that may direct endoproteolytic processing of CLs during transport to the cell surface. Although the mRNAs for CLs are enriched in brain, CLs are ubiquitously expressed in all tissues. To examine how binding of ␣-latrotoxin to CL1 triggers exocytosis, we used PC12 cells transfected with human growth hormone. Ca 2؉ -dependent secretion of human growth hormone from transfected PC12 cells was triggered by KCl depolarization or ␣-latrotoxin and was inhibited by tetanus toxin and by phenylarsine oxide, a phosphoinositide kinase inhibitor. When CL1 was transfected into PC12 cells, their response to ␣-latrotoxin was sensitized dramatically. A similar sensitization to ␣-latrotoxin was observed with different splice variants of CL1, whereas CL2 and CL3 were inactive in this assay. A truncated form of CL1 that contains only a single transmembrane region and presumably is unable to mediate G-proteinsignaling was as active as wild type CL1 in ␣-latrotoxintriggered exocytosis. Our data show that CL1, CL2, and CL3 perform a general and ubiquitous function as Gprotein-coupled receptors in cellular signaling. In addition, CL1 serves a specialized role as an ␣-latrotoxin receptor that does not require G-protein-signaling for triggering exocytosis. This suggests that as an ␣-latrotoxin receptor, CL1 recruits ␣-latrotoxin to target membranes without participating in exocytosis directly.

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“…There are three long (␣) and three short (␤) forms of NRXs transcribed from three homologous genes (18,21). While NRX I␣ binds LTX strongly, other homologs have low affinities for the toxin (22); however, all NRXs strictly require Ca 2ϩ for this interaction (22,23). LPH is a G protein-coupled receptor that binds LTX avidly under all ionic conditions (5).…”

mentioning

confidence: 99%

Mutant α-Latrotoxin (LTXN4C) Does Not Form Pores and Causes Secretion by Receptor Stimulation

Volynski

Capogna

Ashton

et al. 2003

Journal of Biological Chemistry

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␣-Latrotoxin (LTX) causes massive release of neurotransmitters via a complex mechanism involving (i) activation of receptor(s) and (ii) toxin insertion into the plasma membrane with (iii) subsequent pore formation. Using cryo-electron microscopy, electrophysiological and biochemical methods, we demonstrate here that the recently described toxin mutant (LTX N4C ) is unable to insert into membranes and form pores due to its inability to assemble into tetramers. However, this mutant still binds to major LTX receptors (latrophilin and neurexin) and causes strong transmitter exocytosis in synaptosomes, hippocampal slice cultures, neuromuscular junctions, and chromaffin cells. In the absence of mutant incorporation into the membrane, receptor activation must be the only mechanism by which LTX N4C triggers exocytosis. An interesting feature of this receptormediated transmitter release is its dependence on extracellular Ca 2؉ . Because Ca 2؉ is also strictly required for LTX interaction with neurexin, the latter might be the only receptor mediating the LTX N4C action. To test this hypothesis, we used conditions (substitution of Ca 2؉ in the medium with Sr 2؉ ) under which LTX N4C does not bind to any member of the neurexin family but still interacts with latrophilin. We show that, in all the systems tested, Sr 2؉ fully replaces Ca 2؉ in supporting the stimulatory effect of LTX N4C . These results indicate that LTX N4C can cause neurotransmitter release just by stimulating a receptor and that neurexins are not critical for this receptor-mediated action.␣-Latrotoxin (LTX) 1 stimulates exhaustive release of neurotransmitters in vertebrates. This toxin has been extensively used to probe molecular mechanisms that control exocytosis of both synaptic vesicles (SVs) and large dense-core vesicles (LDCVs) in such diverse models as brain, neuromuscular junctions, and endocrine cells (for reviews see Refs. 1-3).LTX acts only after binding to presynaptic receptors (4). Once receptor-bound, the toxin can trigger exocytosis by several mechanisms: (i) activation of the receptors (5-8), (ii) formation of non-selective pores in the membrane (9 -11), and (iii) hypothetical intracellular interaction with the exocytotic machinery (12).Because toxin pores damage cell membranes and produce strong cytotoxic effects (e.g. 13-15), only the receptor-transduced LTX action is likely to reveal intact, physiologically important exocytotic mechanisms. Unfortunately, this action is difficult to study using the wild-type LTX (LTX WT ) because it easily inserts into membranes and forms ionic pores (9 -11, 16). This problem could be overcome by designing LTX mutants that would lack the propensity of membrane insertion, and a promising toxin variant has been described recently (LTX N4C ) (17). This mutant had the same affinity for the receptors as LTX WT (17) but failed to form pores in synaptosomes or receptor-transfected BHK cells (8). Lacking the major (ionophore) activity, LTX N4C was originally thought to be altogether inactive (12, 17). However, we h...

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High Affinity Binding of α-Latrotoxin to Recombinant Neurexin Iα

Cited by 59 publications

References 23 publications

Adhesion G Protein-Coupled Receptors: Signaling, Pharmacology, and Mechanisms of Activation

Adhesion G Protein-Coupled Receptors: Signaling, Pharmacology, and Mechanisms of Activation

α-Latrotoxin Receptor CIRL/Latrophilin 1 (CL1) Defines an Unusual Family of Ubiquitous G-protein-linked Receptors

Mutant α-Latrotoxin (LTXN4C) Does Not Form Pores and Causes Secretion by Receptor Stimulation

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