The G alpha protein GL2 alpha improves the ability to detect the subthreshold expressions of receptors linked to phospholipase C in Xenopus oocytes.
Xenopus laevis oocytes showed no electrophysiological responses to acetylcholine (ACh) and had no significant cholinergic receptor sites when prepared under our conditions. However, they were found to acquire robust electrophysiological responsiveness to ACh when bovine GL2 alpha, which is a member of the Gq alpha family and is highly homologous to mouse G11 alpha, was expressed by mRNA injection. Further analyses indicated that GL2 alpha amplified the activity of endogenous muscarinic ACh receptors that are expressed at an otherwise undetectable level, and thus made their detection possible. Thus, GL2 alpha may prove to be an effective method for detecting the activities of phospholipase C-linked receptors which are only marginally expressed. The usefulness of this method was confirmed in the analyses of a chimeric receptor constructed from metabotropic glutamate receptor subtype 1 alpha and muscarinic ACh receptor subtype M1. The chimeric receptor showed no electrophysiological responses to ACh when expressed alone in oocytes, but became responsive to ACh when co-expressed with GL2 alpha.
Yamashita
S
S
Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
Minakami
R
R
Sugiyama
H
H
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D002678:Chimera; D004056:Differential Threshold; D004305:Dose-Response Relationship, Drug; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D009865:Oocytes / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism*
D011956:Receptors, Cell Surface; D018094:Receptors, Metabotropic Glutamate; D011976:Receptors, Muscarinic; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D000109:Acetylcholine