Article

Autocatalytic Cleavage of the EMR2 Receptor Occurs at a Conserved G Protein-coupled Receptor Proteolytic Site Motif

Sir William Dunn School of Pathology, The University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom.
Journal of Biological Chemistry (Impact Factor: 4.57). 08/2004; 279(30):31823-32. DOI: 10.1074/jbc.M402974200
Source: PubMed

ABSTRACT

Post-translational cleavage at the G protein-coupled receptor proteolytic site (GPS) has been demonstrated in many class B2
G protein-coupled receptors as well as other cell surface proteins such as polycystin-1. However, the mechanism of the GPS
proteolysis has never been elucidated. Here we have characterized the cleavage of the human EMR2 receptor and identified the
molecular mechanism of the proteolytic process at the GPS. Proteolysis at the highly conserved His-Leu↓Ser518 cleavage site can occur inside the endoplasmic reticulum compartment, resulting in two protein subunits that associate noncovalently
as a heterodimer. Site-directed mutagenesis of the P+1 cleavage site (Ser518) shows an absolute requirement of a Ser, Thr, or Cys residue for efficient proteolysis. Substitution of the P-2 His residue to other amino acids produces slow processing precursor proteins, which spontaneously hydrolyze in a defined
cell-free system. Further biochemical characterization indicates that the GPS proteolysis is mediated by an autocatalytic
intramolecular reaction similar to that employed by the N-terminal nucleophile hydrolases, which are known to activate themselves
by self-catalyzed cis-proteolysis. We propose here that the autoproteolytic cleavage of EMR2 represents a paradigm for the other GPS motif-containing
proteins and suggest that these GPS proteins belong to a cell surface receptor subfamily of N-terminal nucleophile hydrolases.

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    • "We have reported that PC1 undergoes cleavage at the HL*T 3041 tripeptide sequence (*: scissile bond, with amino acid numbering based on mouse PC1) within the GPS shortly after synthesis in the ER, resulting in two fragments, PC1NTF and PC1CTF[37]. GPS cleavage of PC1 occurs via a cis-autoproteolytic mechanism without requiring exogenous proteases with similar parameters as in the aGPCR EMR2 in which the mechanism was first discovered[38]. A unique outcome of the cleavage is that the two fragments remain tightly and non-covalently associated to form a heterodimeric molecule termed PC1 cFL[39]. "
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    ABSTRACT: Polycystin-1 (PC1) plays an essential role in renal tubular morphogenesis, and PC1 dysfunction causes human autosomal dominant polycystic kidney disease. A fundamental characteristic of PC1 is post-translational modification via cleavage at the juxtamembrane GPCR proteolysis site (GPS) motif that is part of the larger GAIN domain. Given the considerable biochemical complexity of PC1 molecules generated in vivo by this process, GPS cleavage has several profound implications on the intracellular trafficking and localization in association with their particular function. The critical nature of GPS cleavage is further emphasized by the increasing numbers of PKD1 mutations that significantly affect this cleavage process. The GAIN domain with the GPS motif therefore represents the key structural element with fundamental importance for PC1 and might be polycystic kidney disease's (PKD) Achilles' heel in a large spectrum of PKD1 missense mutations. We highlight the central roles of PC1 cleavage for the regulation of its biogenesis, intracellular trafficking and function, as well as its significance in polycystic kidney disease.
    Preview · Article · Jan 2016
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    • "The large extracellular N terminus of aGPCRs is not unique to this class but is present in all members. A unique feature of the class is a juxtamembrane GPCR proteolysis site (GPS), within the highly conserved GPCR autoproteolysis-inducing (GAIN) domain, that facilitates autocatalytic processing such that the extracellular N-terminal fragment (NTF) and the 7TM/cytoplasmic C-terminal fragment (CTF) are noncovalently associated (Lin et al., 2004; Arac et al., 2012). While the NTF comprises most of the extracellular domain (ECD), the CTF is characteristically composed of a residual ECD, the 7TM domain, and the complete intracellular domain (Fig. 1). "

    Full-text · Dataset · Sep 2015
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    • "The large extracellular N terminus of aGPCRs is not unique to this class but is present in all members. A unique feature of the class is a juxtamembrane GPCR proteolysis site (GPS), within the highly conserved GPCR autoproteolysis-inducing (GAIN) domain, that facilitates autocatalytic processing such that the extracellular N-terminal fragment (NTF) and the 7TM/cytoplasmic C-terminal fragment (CTF) are noncovalently associated (Lin et al., 2004; Arac et al., 2012). While the NTF comprises most of the extracellular domain (ECD), the CTF is characteristically composed of a residual ECD, the 7TM domain, and the complete intracellular domain (Fig. 1). "

    Full-text · Dataset · Sep 2015
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