Human myometrial G alpha s-small (with serine) and Gs-large (with serine) messenger ribonucleic acid splice variants promote the increased expression of 46- and 54-kilodalton G alpha s protein isoforms in pregnancy and their down-regulation during labor.
In previous studies using specific G alpha s antibodies we have identified several human myometrial G alpha s protein isoforms with molecular masses of 45, 46, 47, 54, and 58 kDa, respectively. During pregnancy, levels of the 46- and 54-kDa proteins are significantly increased compared to those in nonpregnant myometrium and then decreased at the onset of labor. In this study we investigated the expression of G alpha s messenger ribonucleic acid (mRNA) splice variants, which are generated as a result of alternative splicing of a single mRNA precursor, in term pregnancy and parturition to determine whether there was any correlation with the observed changes in G alpha s protein isoforms. A myometrial G alpha s complementary DNA was synthesized using RT-PCR and cloned into pCRtmII suitable for preparation of riboprobes for use in ribonuclease protection assays. Using this technique, we identified at least three myometrial G alpha s mRNAs, including two forms of G alpha s-Large (with or without the serine at amino acid 87) and one form of G alpha s-Small (with the serine at amino acid 72). G alpha s Small (with the serine) and G alpha s-Large (with the serine) mRNAs encode for the 46- and 54-kDa G alpha s protein isoforms, respectively, and were increased in term pregnancy and then subsequently decreased after the onset of labor. Our data suggest that posttranscriptional regulation of G alpha s mRNAs may be important in the differential expression of G alpha s protein isoforms during pregnancy and labor.
Europe-Finner
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University of Oxford, Nuffield Department of Obstetrics and Gynecology, John Radcliffe Hospital, Headington, United Kingdom.
Phaneuf
S
S
Mardon
H J
HJ
López Bernal
A
A
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D005260:Female; D019204:GTP-Binding Proteins / Q000235:genetics*; D014644:Genetic Variation; D006801:Humans; D007536:Isomerism; D007743:Labor, Obstetric / Q000378:metabolism*; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009215:Myometrium / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000235:genetics; D011247:Pregnancy / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D012694:Serine
D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D012694:Serine; D019204:GTP-Binding Proteins