RGS21 is a novel regulator of G protein signalling selectively expressed in subpopulations of taste bud cells.
Abstract G-protein-mediated signalling processes are involved in sweet and bitter taste transduction. In particular, the G protein alpha-subunit gustducin has been implicated in these processes. One of the limiting factors for the time-course of cellular responses induced by tastants is therefore the intrinsic GTPase activity of alpha-gustducin, which determines the lifetime of the active G protein complex. In several signalling systems specific 'regulator of G protein signalling' (RGS) proteins accelerate the GTPase activity of G protein alpha-subunits. Using differential screening approaches, we have identified a novel RGS protein termed RGS21, which represents the smallest known member of this protein family. Reverse transcription polymerase chain reaction and in situ hybridization experiments demonstrated that RGS21 is expressed selectively in taste tissue where it is found in a subpopulation of sensory cells. Furthermore, it is coexpressed in individual taste cells with bitter and sweet transduction components including alpha-gustducin, phospholipase Cbeta2, T1R2/T1R3 sweet taste receptors and T2R bitter taste receptors. In vitro binding assays demonstrate that RGS21 binds alpha-gustducin in a conformation-dependent manner and has the potential to interact with the same Galpha subtypes as T1R receptors. These results suggest that RGS21 could play a regulatory role in bitter as well as sweet taste transduction processes.
von Buchholtz
Lars
L
Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany. lars@von-buchholtz.com
Elischer
Andrea
A
Tareilus
Erwin
E
Gouka
Robin
R
Kaiser
Carmen
C
Breer
Heinz
H
Conzelmann
Sidonie
S
D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D015139:Blotting, Southern; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D002478:Cells, Cultured; D003001:Cloning, Molecular; D005260:Female; D005459:Fluorides / Q000494:pharmacology; D020555:GTP-Binding Protein Regulators / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015870:Gene Expression; D017403:In Situ Hybridization / Q000379:methods; D066298:In Vitro Techniques; D011485:Protein Binding; D020710:RGS Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000502:physiology*; D013650:Taste Buds / Q000166:cytology / Q000378:metabolism*; D015293:Transducin / Q000235:genetics / Q000378:metabolism; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism; D015003:Yeasts; D000098706:Taste Receptors, Type 2
D017607:Aluminum Compounds; D020555:GTP-Binding Protein Regulators; D020710:RGS Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; C485337:Rgs21 protein, rat; C431926:taste receptors, type 1; D000098706:Taste Receptors, Type 2; C075192:gustducin; C050992:tetrafluoroaluminate; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C; D019204:GTP-Binding Proteins; D015293:Transducin; D005459:Fluorides