From: The roles played by highly truncated splice variants of G protein-coupled receptors
Receptor | Splicing consequence | General properties of splice variant | Dom/neg? | Refs. |
---|---|---|---|---|
α1A-adrenoceptor | Truncated 6TM mutants. | No cell surface expression. | Yes | [28] |
Calcitonin receptor (CT receptor) | Truncated 6TM mutant. | Rabbit CTRΔe13 is poorly expressed on the cell surface and fails to activate cell signaling. | Yes | [29] |
Chemokine receptor 5 (CCR5) | Severely truncated mutants. Ccr5Δ32 is a 5TM mutant. | Natural mutants of human chemokine receptor CCR5 lacking the last 3 or 5 TMDs are non-functional. Ccr5Δ32 complexes with CCR5 and retains CCR5 in the ER, thus reducing cell surface expression. | Yes | |
Dopamine receptor (D3) | D3nf is a truncated 5TM mutant. | Human D3nf mutant has a punctuate perinuclear distribution and does not bind DA-ligands. | Yes | |
GABAB receptor (GABABR1) | GABABR1c has an additional 31 amino acids in TM5. | Â | No | [34] |
Gastric inhibitory polypeptide receptor (GIP ) | Truncated 4TM mutant. | This inactive mutant receptor inhibited GIP signaling and decreased cell surface expression by retaining WT receptor in the ER. | Yes | [35] |
Ghrelin receptor (or GHS-R1a) | GHS-R1b is a truncated 5TM mutant. | GHS-R1b is a non-signaling splice variant of GHS-R1a. | Yes | [36] |
Gonadotropin-releasing hormone receptor (GnRH receptor) | Truncated 5TM mutant. | 5TM variant of human GnRH receptor shows decreased cell surface expression, no ligand binding and no signal transduction. | Yes | [37] |
Growth hormone-releasing hormone receptor (GHRH-R) | Truncated 5TM mutant. | The mutant GHRH-R cannot transduce GHRH signals. | Yes | [38] |
Histamine receptor (H3) | 6TM-rH3R is a truncated 6TM mutant. | Several splice variants of rat H3R do not bind agonist, have an intracellular localization and co-expression with WT receptor decreases cell surface expression and functional responses. | Yes | [39] |
Histamine receptor (H4) | hH4R(302) lacks 88 amino acids from TMD2 to TMD4. hH4R(67) is a ~ 1.5TM truncated mutant. | These human H4R splice variants were localised predominantly intracellularly when expressed in recombinant cells. No ligand binding or cell signaling detected. | Yes | [40] |
Leukotriene B4 receptor (BLT1) | LTB4R-AS1 lacks TMD2 and part of ECL1 (39 amino acid deletion). | Both isoforms of human BLT1 (LTB4R) are expressed in human airway smooth muscle cells. | Yes | [41] |
LTB4R-AS2 is the 3TMD to C-terminus (lacks 100 amino acids). | ||||
Luteinizing hormone receptor (LH receptor) | Truncated 5TM mutant. | The 5TM mutant of human LH receptor binds ligand (limited) but has no signaling activity. | Yes | [42] |
μ-opioid receptor (μ-OR) | Truncated 6TM mutant. | A 6TM μ-OR variant in mice identified ligands lacking the traditional side effects of classical opiates but maintaining analgesic property. | No | [6] |
Motilin receptor | GPR38-B is a truncated 5TM mutant. | Â | ? | [43] |
Neurokinin 2 receptor (NK2) | An ICL2-TM4 deletion mutant. | NK2β splice variant is poorly expressed on the cell membrane and is non-signaling. | Yes | [44] |
Neuropeptide Y receptor (Y1) | A truncated 5TM mutant. | The putative hY1-related 5TM accessory protein encoded by the non-spliced hY1 mRNA is not involved in facilitating hY1 production. | No | [13] |
Neurotensin receptor (NTS2) | Truncated 5TM mutant with long tail. | Rat vNTS2 is functionally active and can heterodimerize with NTS2. | No | [45] |
Nociceptin receptor (NOP) | Truncated 4TM mutant. | The rat truncated NOP receptor is localised to cell membranes but is non-functional. | Yes | [46] |
Prostaglandin F2α receptor (FP) | A 6TM truncated mutant (FPs) | hFPS is functionally inactive and highly expressed in the perinuclear region. | Yes | [47] |
A truncated mutant (PTGFR-v2). | No distinct functional role identified. | No | [48] | |
Somatostatin receptor (sst5) | Human sst5TMD5 is a 5TM truncated mutant. | Identified novel truncated but functional human sst5-variants; present in normal and tumoral tissues. | No | [49] |
Human SST5TMD4 is a 4TM truncated mutant. | ||||
Murine sst5TMD4 is a 4TM truncated mutant. | Three murine variants were functional to mediate ligand-selective-induced variations in Ca2+ and cAMP despite being truncated and displayed a preferential intracellular distribution. | No | [50] | |
Murine sst5TM2 is a 2TM truncated mutant. | ||||
Murine and rat sst5TM1 has just TM1. | ||||
Vasopressin receptor, subtype 2 (V2) | V2b is a truncated 6TM mutant. | V2b is retained in the ER where its C-terminus can be either intracellular or extracellular. | Yes | [51] |