Endothelin-B receptors activate Galpha13.
Endothelin (ET) receptors activate heterotrimeric G proteins that are members of the Gi, Gq, and Gs families but may also activate members of other families such as Galpha12/13. Galpha13 has multiple complex cellular effects that are similar to those of ET. We studied the ability of ET receptors to activate Galpha13 using an assay for G protein alpha-chain activation that is based on the fact that an activated (GTP-bound) alpha-chain is resistant to trypsinization compared with an inactive (GDP-bound) alpha-chain. Nonhydrolyzable guanine nucleotides and AlMgF protected Galpha13 from degradation by trypsin. In membranes from human embryonic kidney 293 cells that coexpress ETB receptors and alpha13, ET-3 and 5'-guanylylimidodiphosphate [Gpp(NH)p] increased the protection of alpha13 compared with Gpp(NH)p alone. The specificity of ETB receptor-alpha13 coupling was documented by showing that beta2 receptors and isoproterenol or ETA receptors and ET-1 did not activate alpha13 and that a specific antagonist for ETB receptors blocked ET-3-dependent activation of alpha13.
Kitamura
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K
Fourth Department of Internal Medicine, Kumamoto University, Kumamoto, Japan.
Shiraishi
N
N
Singer
W D
WD
Handlogten
M E
ME
Tomita
K
K
Miller
R T
RT
D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D016232:Endothelins / Q000494:pharmacology / Q000502:physiology; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007668:Kidney; D007700:Kinetics; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014357:Trypsin
D016232:Endothelins; D006150:Guanine Nucleotides; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D014357:Trypsin; D019204:GTP-Binding Proteins; D044365:GTP-Binding Protein alpha Subunits, G12-G13