[A study on GTP-binding protein in the activation of phospholipase C and phospholipase A2 in cultured rat luteal cells].
We have studied the possible involvement of the GTP-binding protein (G-protein) in the activation of phospholipase C and A2 in cultured rat luteal cells as a transducer of cell information. 1. Inositol phosphate production and arachidonic acid release in rat luteal cells by the stimulation of PGF2 alpha and GnRH receptors are dependent on GTP and therefore suggest the involvement of GTP binding protein. 2. When the cells were not treated with IAP, a membrane protein of 41K molecular weight was apparently labeled. The protein, with a molecular weight of 41K, which was obtained from cultured rat luteal cells without prior treatment with IAP is considered to be the alpha-subunit of GTP binding protein as reported in other cells. While alpha-subunit of G-protein was ADP-ribosylated in luteal cells too, the 41K protein from the cells pretreated with IAP was not found to be ADP ribosylated. 3. When such IAP pretreated luteal cells were stimulated by PGF2 alpha or GnRHa, the production of inositol phosphate and the release of arachidonic acid were observed with no suppression. 4. The results suggest the existence of some G-protein other than Gi between the receptor and phospholipases C and A2.
Watanabe
H
H
Department of Obstetrics and Gynecology, Sapporo Medical College.
Yamamoto
H
H
Endo
T
T
Tanaka
S
S
Hashimoto
M
M
D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002478:Cells, Cultured; D015237:Dinoprost / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D008184:Luteal Cells / Q000201:enzymology* / Q000378:metabolism; D008970:Molecular Weight; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D011919:Rats, Inbred Strains; D010738:Type C Phospholipases / Q000378:metabolism*
D001095:Arachidonic Acids; D007295:Inositol Phosphates; D007987:Gonadotropin-Releasing Hormone; D015237:Dinoprost; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins