Abstract
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.
Footnotes
The work is supported in part by the National Institutes of Health National Institute of Neurological Disorders and Stroke [Grant R01-NS072394].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
ABBREVIATIONS:
- GPCR
- G protein-coupled receptor
- 7TM
- seven-transmembrane
- GPS
- GPCR proteolytic site
- GAIN
- GPCR autoproteolysis-inducing
- HEK
- human embryonic kidney
- EMR2
- EGF-like module-containing mucin-like hormone receptor-like 2
- LTX
- latrotoxin
- SRE
- serum response element
- BAI
- brain-specific angiogenesis inhibitor
- NFAT
- nuclear factor of activated T-cells
- FLRT
- fibronectin leucine-rich repeat transmembrane
- TG2
- transglutaminase 2
- PAR
- protease-activated receptor.
- Received May 30, 2012.
- Accepted July 20, 2012.
- Copyright © 2012 The American Society for Pharmacology and Experimental Therapeutics
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