Changes in uterine G-protein content during pregnancy in the guinea pig.
G-protein content (G(i) alpha, Gs alpha, Gq/11 alpha G(o) alpha and beta subunits) has been measured in membranes prepared from guinea pig uterus at different stages of pregnancy using SDS-PAGE and immunoblotting. Quantification using HRP- or 125I-labelled IgG as second antibody showed a good correlation between added membrane protein and measured G-protein content. Gs alpha appears as two bands of 45 kDa and 52 kDa respectively, the content of both were comparatively high in the non-pregnant uterus and fell about 4-fold close to term (60-67 days). G(i) alpha showed the converse with low level in membranes from the non-pregnant uterus with level approximately 6-fold higher by term. G(o) alpha exhibited changes similar to G(i) alpha. The changes in the content of Gq/11 alpha where biphasic, with comparatively high levels in membranes from the non-pregnant uterus, a sharp fall early in pregnancy followed by a 3-fold rise by near term. The uterine membrane content of the common beta subunit exhibited changes comparable to that of G(i) alpha and G(o) alpha with a 6-fold rise in content between non- and late-pregnant. Measurement of the effect of GTP gamma S action on phosphatidylinositol phospholipase C activity in uterine membranes with exogenous substrate showed pregnancy-dependent effects. In membranes from the non-pregnant uterus 0.1 microM GTP gamma S caused a modest stimulation of activity of 16 +/- 1.9%, whilst at 100 microM it inhibited the enzyme by 25 +/- 6.48%. In membranes from the late-pregnant guinea pig uterus GTP gamma S at both concentrations caused stimulation of enzyme activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Warsop
H
H
University of Oxford, Laboratory of Cellular and Developmental Physiology, UK.
Khouja
A
A
Wichelhaus
D P
DP
Jones
C T
CT
D000818:Animals; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006168:Guinea Pigs; D007295:Inositol Phosphates / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
D007295:Inositol Phosphates; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase