Identification and Expression of Go1 and Go2 α-Subunit Transcripts in Human Myometrium in Relation to Pregnancy

The 39-kDa G o α protein, the α subunit of a major heterotrimeric G protein of brain and neuroendocrine cells, was found to be present in human myometrium. Using three different antisera, we showed its strong expression in myometrium from pregnant patients as compared to nonpregnant ones. This is in agreement with the high expression level of its two isoforms (α o1 and α o2 ), previously described in late pregnancy. To better ascertain the nature of these immunoreactive isoforms, we investigated transcripts of the G o α gene in myometrium from pregnant and nonpregnant patients by reverse transcription-polymerase chain reaction (RT-PCR). In this tissue, the amplified cDNA product of a region common to both G o1 α and G o2 α mRNA variants was recognized as the G o α nucleotide sequence. Transcripts of G o1 α and G o2 α were identified by sequencing. A partial cDNA G o2 α sequence was described, which differed from the G o α gene by two nucleotides in exon 8B. Levels of G o1 α and G o2 α transcripts analyzed by semiquantitative RT-PCR were significantly higher in myometrium from pregnant than from nonpregnant patients. It is suggested that G o α gene expression in this tissue may contribute to modifications seen in the signaling pathways observed at the end of pregnancy.